I run LibreOffice (5.2.0.4, but I’ve seen the same in other versions too) in Dutch. The user interface is translated pretty well overall, except the keyboard shortcuts as mentioned in the menus and in Extra → Aanpassen → Toetsenbord: those are French instead of Dutch:
(I’m not sure what the correct Dutch translations are; English would be much better than French, and maybe even better than forced Dutch translated terms.)
Not for me - Dutch and English user interface installed, Windows 10, LO 5.2.1.2, keys are listed in English for both languages: Up, Down, Home, Insert. Makes sense to me: that’s what’s on my keyboard. Now if you have a keyboard with key captions in French, it’d make sense to list the keys in French as well.
File a bug report on this at Bugzilla.
Strange errors of the kind are sometimes due to a user profile corruption.
You may try a fresh (reset) user profile under the appropriate precautions and check if this helps.
Refer to https://wiki.documentfoundation.org/UserProfile or https://wiki.documentfoundation.org/UserProfile/nl