I would start with having generic FX1, FX2, FX3… on/off automations pre-populated on the automation list, in the off state, with default value 0… for every pattern.
I believe these automations would be manageable even without explicit names of FX. And they could be made optional as well - we could only enable this via instrument definitions, so we don’t make FX too confusing for new users.
Ideally, the integration between automation lane and mute state on the FX slot would be extended. The mute action from FX slot would overwrite the automation lane. We could have “mute FX on pattern” and “mute FX on ALL patterns” actions in the menu.
That would simplify the ability to use FX per pattern, without adding much clutter.
The FX parameters automation lanes would be added manually if needed and they works be effect specific with names and everything
Ideally, we could add them / enter the automation lane straight from the FX screen by holding Effects button and pressing the encoder of the FX parameter, or some other button combo + encoder press.
EDIT: Just read this post and realized I have probably missed some technicalities of the current implementation, will check again in the evening.