Zammad have been working on a new UI stack since at least 2020 in which a proper editor would be implemented. I believe it’s taken a lot longer than expected. In hindisght they probably should have implemented a stop-gap solution similar to what I’d implemented, as the hotkey-based solution has never been great from a user experience perspective in my opinion, and like you’ve noticed some of them just don’t work due to conflicts and browser issues.
As a developer myself, I understand the reluctance to take time away from working on the long term solution to implement a short term solution, but I’ve learnt that can often be the wisest approach, as long term solutions can blow out or sometimes not even happen due to other more important issues popping up and a change of direction.
A bit of history can be found in this thread: Text editor enhancements