I just started working with CryptPad this evening, and my spell checker is not working at all. As a note, I am running Pop!_OS Linux (an Ubuntu derivative), and the Chrome browser. If I cannot get a spell checker to work, I am not going to be able to use CryptPad -- my spelling is THAT BAD 8-/
Anyway, I have tried the above. My Settings=>Rich text=>Spellcheck is enabled. No red-underlined text pops up, even when I intentionally misspell a word. As a note, I am reading the forum using the same browser instance, and it is flagging my misspellings. The issue is that it is not working inside the document.