I'm surprised the bug you linked isn't prioritized yet. I haven't seen a developer response for this specific issue. Maybe I'm not looking hard enough?
This doesn't seem to be Android-specific. No responsive feedback when sync gets stuck doesn't help.
Third-party workarounds to Dropbox like Dropsync and Syncthing can work for some. Caveats like Syncthing's wifi-only sync, lack of iOS support, storage bloat by encrypted copies, and other snags can also be dealbreakers.
If slow or stuck sync is just a symptom of no direct filesystem access and everything going through Android FUSE, causing slow performance, then perhaps that should be visibly communicated? I doubt it is, though.
I can't speak to most of the encryption points but I'm looking forward to someone else filling in, as well as a first-party solution for this issue.