Two people communicating one-to-one and starting a new account to solely dedicate to maintaining a pretty public open source project doesn’t sound too fishy, tbh, if everything else checks out. (Catfriend1 confirms the handover, etc.)

No, not really. Programming requires understanding of the underlying hardware, at least to a certain extent. Otherwise performance issues will look like dark magic and optimizing anything would be impossible.

Where do you start debugging if something goes wrong with the software and your information level is this low/ do you look at network stats? CPU utilization, paging/swapping? Is the hard disk bandwidth the bottleneck? Without at least some passable understanding of a computer architecture people like this just throw up their hands, or throw whatever tricks they know at the wall and see what sticks.

Yeah exit nodes can be lots of effort(probably, never ran one) but relay nodes do get issues. Some banks do outright block any nodes that run tor, regardless of the exit node or relay node status.