[schapplm]

one other thing I struggle with is, if I manually mark a show/episode as "unwatched", the other clients mark it back as "watched" again when they update, despite me having "follow user setting watched/unwatched" set to enabled.

This should not be the case. The settings look ok, though. Perhaps it is possible to debug with a detailed log of both clients.
In my tests a few years ago, it worked, but I did not use a central SMB SQLite file. This should not matter, however.
The WatchedList database contains a column `lastChange` which is dedicated to store the timestamp of the "unwatch" event.
This should only be overwritten, if the setting of "watched" on the other client is newer than setting "unwatched" on the first client.