Have you experimented with light probes?
https://docs.larian.game/Light_probes

They can work wonders on the lighting.

Per the doc you should have one per ATM trigger. And local probes as needed.

My D:OS Mods:
Dunamis - A 15 hour Adventure Mod for D:OS EE

A Necromancer's Crusade - 10 hour adventure mod for D:OS EE

4 Character Creation (EE)