Sure, you can send me an email with my address on this page: https://kaiclavier.com/docs/
Some sample text to work with would be fantastic, and a screenshot of your inspector setup so I can copy that.
I just wanted to make sure the support script was the most recent version so I can work from that! There was a chance you were using the outdated version. I'm interested in the changes you made, but I'll see what I can do with the latest code first!
Hm, it looks like it's not properly flipping tags around to work right with this setup for whatever reason. I remember having that work before so I wonder what the issue is... I'll be able to give this a closer look later this week if that's okay! It's been a while since I edited it, so it may just be some configuration isn't set up.
The third visual example there is an error I haven't seen in a long time, but I think something is getting confused with the font... Hopefully it'll resolve itself with this other issue fixed, otherwise I have a few ideas on what the cause could be. (Note for future me: internal/external material batcher being confused by helper script moving indices around? Might have to change uv3.x value retroactively.) It could also just be that the font doesn't properly support bold text or something.
Another note I'll quickly say about Arabic text, usually it's the Unity inspector that breaks a lot of it in the first place by displaying things left-to-right and generally just not having proper support for it. (But a fixer is still needed since the tag system and display system goes left-to-right right now. Maybe an alt fix could be if I edit code to be properly flippable to be right-to-left only when rendering, instead of shifting around character order? Not sure how difficult this would actually be, but it would probably take a fair amount of time.) Anyway, if you can have a script that reads your language file directly from a txt or another non-unity format and prints that directly to a text mesh object, ligatures can be imported without needing to be fixed, if I remember correctly. (I could also not be remembering correctly.) I think the same was also true for the emoji support script.
Anyway sorry that's a bit rambling, I included a few notes for myself too... Hopefully I can get this working for you soon! With any luck it'll just be a configuration issue and if not I can edit the support script soon.