@Markismus amazing work, thank you so much!
I'm using your
VanDale Groot Woordenboek Nederlands-Frans (2010)_reconstructed_Feb19th2021.dic, but it has a lot of XML entities instead of Unicode characters. They appear as entities in the Pocketbook dictionary application, and don't appear at all in the quick dictionary popup of the normal ePub reader. I haven't tried in Koreader.
I looked at your script but I'm not super familiar with Perl. Perhaps
https://github.com/Markismus/PocketB...ookdic.pl#L375 could be replaced with
https://metacpan.org/pod/HTML::HTML5::Entities?