Black screen behind UI Elements is a known issue and being looked into, is not related to wine as it is also occurring for Windows users.
The issue with starting clients after deleting wine occurs only if you start the client before the launcher has downloaded and updated wine (this is a bug, you’re not supposed to be able to). Switching between 32 and 64 will effectively cause then launcher to update the files that were locked the first time which is why that works if no client is running.