> What problems do you see with the current approach that would require
more fine-grained user control?
The main issue for me is removing the `error` feature from any mode
that adds it with `:override t`. I find the override font-locking is jarring - in some
Languages half the buffer can switch in and out of parse errors when you
do something as simple as removing a closing paren.
Also, allowing users to rearrange features at different levels seems like a bonus.
> And why do you think a defvar is the proper way of providing such control?
You're right, I don't think it's the best way - it's just what I've been doing in
treesit modes I've written till now.