I noticed some inconsistencies concerning tool-tips for the Book view formatting toolbar controls: even the entries are translated, tool-tips remains in English.
These problematic entries are "rvAction[...](n).Caption", all with number (n, 1 or 2) in name. But, for example "rvActionFormatPainter" has both "rvActionFormatPainter.Caption" and "rvActionFormatPainter.Hint" and no number in its name, and it displays tool-tips correctly.
Could it be a reason?
By the way, "cmbFontsSize" lacks ".Hint" on the end, so it didn't show tool-tip. Adding the ".Hint" (final form "cmbFontsSize.Hint") solves the problem!
Also, right-click menu on Book view has some elements untranslated (Select All, Tables (with all sub-options), Copy...), whereas the other (Find, Paragraph, Bullets...) are in English upon starting the program, but after Ctrl+Shift+L they turn into applied language.