Tl;DR: Is there a way to view the logs? What fonts are you using?
Long Version:
I'm playing on Linux (Ubuntu 20.04), and while the browser version (launching index.html from the itch.io app) works fine, it doesn't support fast-forward with ctrl (which I believe you're aware of, so I suppose there's little to be done about it).
I tried launching it with Wine, but it gets stuck on the very first "Now loading..." Screen. Is there any way I could attempt to debug that and figure out what's wrong? I didn't find any log files or anything I could check for obvious errors. Is there a way to enable logging? Maybe I could figure out a way to get it running with Wine and share it with others.
Mind you, I'm not asking you to support Wine or Linux, I'd be happy to work it out on my own. I understand you're busy already, and don't have the resources (as you said below about Mac and Spanish versions). I'm just asking if there's an easy starting point somewhere.
Though a native Linux version would be a dream, of course - a wet one ;-)
edit: Superficial investigation suggests a font issue. I don't know if that's the core problem, or just a secondary issue, but I'd like to fix it anyways. Could you tell me the names of the fonts you're using so I can check if I am missing any?