This resulted in 5-10 changes in the existing code where parameters were off.
Hopefully I didn't make too many mistakes when writing the hook prototypes as it was a tedious job.
An (unintentional) benefit of this new system is that you can see the hook prototypes in include/modules.h like:
/* Hook prototypes */
int hooktype_local_quit(aClient *sptr, char *comment);
....
Though, the wiki is likely a better place: https://www.unrealircd.org/docs/Dev:Hook_API
with a default of 3:90 (3 joins per 90 seconds). There's rarely any need
to configure this on a per-channel basis and this way it's enabled by
default for everyone (unless you decide not to load load the module)