Just what the title says: sight range debuffs don't affect monster's attack patterns at all. Depending on how invisibility actually works, this may be why invisibility is also currently nonfunctional.
Well it's somewhat functional but modifications to monster don't work. They can see directly next to you and that emulates the default of one trap sight. Firing spells at invisible targets is a bug. Being able to have specific sight and trap sight values would be quite nice though.
Specifically, I was messing around with an on-hit spell that inflicted Shroud of Darkness, which should've eventually blinded them. Didn't do anything other than inflict some EDR penalties.