Depending on how far along you are, I'd recommend checking out: https://lexical.dev/

I'm in the process of migrating my companies RTE from Slate to Lexical.

I've been able to remove thousands of lines of custom code and increase the performance and reliability

If you are using Slate then I recommend adding Plate https://plate.udecode.io/ on top of it. It makes it so much easier to use and to get rich functionality.

Check how well your Slate version supports CJK input and input generally on Android. The last time I tested Slate, it had glaring issues on Android.