Language

Rainbowisland has five officially recognised languages. Two are considered native. These developed naturally amongs the Celts who settled in Rainbowisland more than 1000 years BC.
These languages are Flemish and Celtic.

Flemish

This language evolved in the south and the east of Rainbowisland. Today it is spoken in every province, but mostly still in the southern and eastern provinces. It is almost identical to the language spoken in North-Belgium. Throughout the centuries this language was called many things. High-Celtic in Roman times, Germano-Celtic in the early middle ages, Islandian in the middle ages and West-Dutch since the 17th century. Belgican was the most common term in Rainbowisland itself.
Belgican has always remained very similar to the language spoken in Flanders (= modernday North-Belgium). So much in fact that they are mutually intelligable and sound like dialects of eachother. In 1894, members from the regional government of Kastelland met with Flemish politicians. They agreed to call both their languages "Flemish" and to synchronise grammer and vocabulary and to keep doing so from then on. The synchronising was easy since 99% of day-to-day use of the languages was identical (although pronounciation differt from province to province in both Flanders and Rainbowisland). The Kastelland government accepted the proposal and on the 11th of july 1897, Flemish became the official name for the most common language in Kastelland. However, due to an unfair political system in Belgium, Flanders has not been able to make the change. Which leeds to the very stange situation that the official language of Flanders is Dutch (which is also very similar, but day-to-day use varies quite a lot).
Today, Flemish is the first language of Rainbowisland, spoken by 59% of the population. It is spoken most in Kasen, Kastel, Kastelia, Puipil, Rainbowland and Landsend and least in Gaali and Natria.

Celtic

The Islanders who were less inclined towards seafaring and trade did not follow Flanders in it linguistic developement. These people kept speaking Ancient Belgian (a kind of Celtic) even after Flanders changed to a more germanic language.
In the middle ages, the Celtic speaking people started to trade more, but primarily with the British islands (especially Ireland) and came into contact with other Celtic speaking people. In time these languages grew closer toghether but never to the degree of Flemish and Belgican.
In 1928, the government of Ireland started talks with Crawrealm and Montana for some sort of liguistic matching of Gaelic with Celtic. After some study, Irish and Islander scientist concluded that the languages were to different to do any such thing. The matter was dropped.
Today, Celtic is the second language of Rainbowisland, spoken by 21 % of the population. It is spoken most in Craw, Westgate, Natria and Montana and least in Kasen, Landsend, Forria and Eastsealand.

The three non-native languages came to Rainbowisland in later colonisation waves. These are Far-Oerian, English and French.

Far-Oerian

This Language is named after the Faroe islands. Far-Oerian is actually a dialect of Danish and is very similar to Norwegian, Icelandic and Swedish. In the early middle ages, Danish vikings started to raid the north and east coast of Rainbowisland. After 300 years of mostly unsuccessful raids, the frustrated Danes tried a fullscale invasion. After a short but fierce war, an agreement was reached. Danes were allowed to settle in the unsettled areas of Kastel, Forria and Natria (which was still plentyfull at the time). But they would be subjegated to the Rainbowisland monarchs who ruled those lands. The language of these new arrivals was more or less compatible with the Belgican spoken in those lands at the time. So Belgican was used as a common language and Danish remained in use in the isolated villages. These villages grew into strong cities which kept useing Danish as their primary languages. Over time, this Danish moved away from proper Danish and stayed in sink with the language spoken on the Faroe islands. People kept calling the language Danish for lack of a better word. Later, when Denmark recognised Far-Oerian as a separate language, Forria and The Eastsea changed the name of Rainbowisland Danish to Far-Oerian and the rest of the island soon followed suit.
Today, Far-Oerian is the fourth language of Rainbowisland, spoken by 5% of the population. It is spoken in Forria, Kastel and Natria. There are small Far-Oerian speaking pockets in Eastsealand and Kasen. Far-oerian is not spoken in any other province (not, or by less than 0.01% of the population)

English

Rainbowisland has been trading with the lands that make up the UK today since the 11th century. Most seafarers prefered Ireland to the other islands but this changed in the 17th century, when the English started visiting Rainbowisland harbours. Soon, there were Islanders living in English harbours and vice versa. In the most international harbours, English started to replace Belgican as trade language (because it is easy to learn enough English to get around in).
In later years, England got involved in several wars and was in desperate need of friendly ports. Kastelland set aside lands close to it's main ports for English marines. Southrealm soon made a deal with Puipilland to do the same (Landsend didn't have any land left to set aside). In return, England agreed not to press or otherwise recruit Islanders for its crews. These barracks evolved into little towns when England began to allow women to accomany their husbands to Rainbowisland. About 150 years later, the UK no longer needed these bases and tried to recall these troops. However, most of them were born and raised on the Island and refused to move to the UK. Some of the marines were incorporated into the navies of Southrealm, Kastelland and Puipilland. The remaining marines were given the choice to become civilians or to enter the marinecorp of Forria and the Eastsea, Montana or Crawrealm. Those who chose civilian lives often had to move inland in search of jobs. As a result, English spread across the Island and caught on in many regions.
Today, English is the third language of Rainbowisland, spoken by 12% of the population. It is spoken most in Kasen and Landsend and least in Gaali and Natria. It is not spoken in Kastelia and Montana

French

French arrived last on Rainbowisland in what is know as the fifth wave. In 1789 the French people rebelled against the monarchy and Napoleon rose to power. French noblemen and their followers fled to the UK and Rainbowisland. These nations reluctantly allowed these undemocratic nobles into their democratic monarchies. Soon after, these émigrees were followed by French speaking noblemen and French and Flemish speaking refugees from what is now Belgium. In the later years of Napoleons reign, French, Italian and Spanish deserters and refugees arrived in Rainbowisland. All these people were originally housed in the old English bases and in camps in Kastelland and Puipilland. This put a big strain on the resources of these realms. So an agreement was reached with the other realms that each would take in a number of refugees in accordance with the vacant lands each had. this ment that Southrealm and Kastelia did not take in any refugees. Most ended up in Natria and Gaali (being the poorest and least developed parts of Rainbowisland). French being completely incompatible with any other language of the Island remained in use with almost all of the émigrees, deserters and refugees, creating monolingual French areas in parts of the Island.
Today, French is the fifth and smalles language of Rainbowisland, spoken by 3% of the population. It is spoken most in Gaali, Natria and Kasen. It is spoken least in Montana, Craw and Westgate. It is not spoken (or by less than 0.01% of the population) in Landsend and Kastelia

Minor Languages

Like in most western nations, there are pockets of different languages (mostly in cities with a large port or airport). In Rainbowisland there are 12 languages spoken by at least 10.000 people. These are not recognised as official languages and communication with the government can not happen in these languages. The state does not subsidice monolingual schools or projects in these languages. City councils can and do often subsidice these schools (if one of the official languages is in the curriculum) and projects but are in no way obliged (by law) to do so. These minor languages are: Japanese, Chinese (mostly from Taiwan), Spanish (mostly from Venezuela), Turkish, Italian, German, Letzeburgish, Yiddish, Russian, Polish, Portugese (mostly from Brazil) and Gaelic.
There are probably large Danish, Greenlandic and Icelandic speaking communities. But it is hard to get exact numbers since most of these people call themselves Far-Oerian speaking in a sensus. For the same reason, it is hard to tell how many Afrikaans speaking people there are on the Island (number ranging from 8.000 to 15.000 have been suggested).
Everyone is free to speak whatever language he (or she) chooses. In total, more than 150 languages are spoken in Rainbowisland. Some of them by only one or two families. The exact number is unknow.
There are two notable experiments running. At the University  of Roman Languages in Longlang, the common language is Latin (for everyone except freshmen). And at the University of Language Studies in Eesten, there is one department that has Klingon as it's common language!