1. I could build a harbor in any territory that already had a Cothon.

2. As Russians, I couldn't take any territory owned by Babylonians (the stubborn guy). The tooltip said "Can't be done on allied territory.", but I wasn't allied with them. I was able to steal territories from two other players.

3. I advanced from Joseon to Russians while researching Centralized Power. When the tech was finished, the message said "Russians completed".

4. A battle preview got stuck on my screen until reload.

5. Sometimes my units became invisible until reload.

Thanks for reporting!

Note that for the developers, it is likely easier to have one bug per thread than having the same bugs reported over and over again in multiple threads, in particular when those threads mix information about different bugs and have non-desriptive titles like "All bugs from my playthrough".  For example, items 3 and 4 on your list have already been reported in this thread and in this other thread.

But i don't recall hearing about items 1 and 2 on your list so far, so reporting them is likely quite useful  :-).