Looks good!

I think this is close now!

• please remove sygnal.log :)
• looks like you've been bitten by changes in Twisted (they added type annotations) which has left you with the trouble of cleaning up mypy after it. Fixing this was very noble of you, but (especially for code which you haven't touched in this PR), it's preferable to do it in a separate PR (this way, we're not waiting on this entire PR being approved before we fix CI [potentially affecting other PRs too]. It also makes reviewing this one a little bit less confusing :)). What we should have done is pin the versions of the dependencies so that this doesn't happen — if you fancy taking that on in another PR (probably using >=...,<... syntax so minor upgrades are still allowed? Refer to Synapse for an example), that would be appreciated and will save the next innocent person from having CI give them trouble :).
• my mistake for misleading you about the config_setup thing -- we want to reinstate it (since it's still overridden and used by subclasses) & the calls to it from the overriding methods (in case we ever add code to the function) -- just use the word pass in the parent's function, because that's the standard way of saying 'this is intentionally empty' -- you could just as well write 42 or super but it's unusual and confused me into thinking you didn't finish the line 😅 .

just a handful of minor changes now, you'll soon see this one merged and released :)

Great!