Go there for general information about all Libretto models and for links to other Libretto pages. While you are there, find the Libretto mailing list information, I will not repeat it here. Mailing list can provede excellent support for any problems, including how to replace the Japanese Windows with the English version.
Also search for 'browser' to learn how to configure your browser to view Japanese web pages. You would need that to follow the other links on this page. Most of them are links to web pages written in Japanese. Even if yo could not read Japanese, you need to configure your browser to properly display Japanese characters. Japanese character set has two sets of characters for Latin alphanumerics: one set of single byte ASCII characters and one set of double byte JIS or shift-JIS characters. The second set would display as 'trash' if your browser is not properly configured. There is a test for your browser at the top of my page with Japanese links. When your browser is properly configured with Japanese fonts, and you select character set as Japanese Shift-JIS or Auto-Detect, the two test lines should display the same characters with somewhat different size.