I have done translation. I emailed this language file to you

By the way, while testing, I noticed that some of the windows may cause a character corruption (Japanese font not displayed correctly).
Following images are screenshots of such windows.
[1] Show -> [Statistics graph, Tasks graph, Data transfer graph, Deadline graph]
English mode

Japanese mode (the red characters in blue circle are corrupted)

[2] Extra -> BOINC Preference -> Processor -> Day-of-week-override
Extra -> BOINC Preference -> Network -> Day-of-week-override
English mode

Japanese mode (the characters in blue circle are corrupted)

Thank you.