Whenever I import a book co the Calibre eBook manager library it converts the names/titles to English removing all the accents from European words and replacing non-Latin (e.g. Russian) words with their romanizations.
There is no technical necessity in this in the today world of Unicode and it also harms usability as it is always easier to read (and search for) a word in its original script rater than a romanization if you are fluent in it (and I obviously am sufficiently fluent in all the languages I read books in).
Preferences - Saving books to disk - Convert non-English characters to English equivalents checkbox allows you to turn this off for books exporting but it will still romanize the names of all the files in both the local library and the reader device library.
How can romanization be possibly turned off for the libraries files names?