I want to first mention how much I've enjoyed Underrail; despite playing since early access back in 2015, I finally managed to stop the theorycraft/restart cycle and actually finish the game for the first time. The last fight was phenomenally atmospheric, I loved it!
That being said, I think it might be nice if the boss was a little more resistant to cheesing. There is a great multi-objective setup in the boss room that I completely ignored in favor of sniping him in the eyeball and killing him in a single turn - for reference, this was on Dominating and without finishing the puzzle. I think if he had a damage cap of say, 1000/turn (possibly affected by difficulty level) before the tanks were destroyed or puzzle was completed, it might force a bit more interaction with the intended methods of winning that fight.