I've just started using this project for my WordPress site (and loving it so far!) to create exercises for learners of English.
I've begun with Drag Words and Fill in the Blanks types, where you need to mark the words with an asterisk at the beginning and end.
While it's pretty quick and easy to do, it would be even easier if you could just highlight the word and click a button to add/remove the asterisks (and possibly another button for hints). This could be on the toolbar (see attached picture) and/or in a context menu/.
An alternative is to allow the editor to be replaced with the default Gutenberg one, where I believe it's pretty easy to add functionality through plugins.
Edit: I’ve just found this page so maybe I’ll have a go myself when I get time.