They have money and manpower to do it. It is huge deal for immersion.
Tactical adventures with a team of 17 people put it on Solasta.
I would be ok even if they had did a binary system like the same way you choose to go to camp but insteady switch to night.
Or being able to leave the camp at night.
The Goblin battle should be at night.
My thought was the same, keep it simple, no in game live transitions. When camping or at an Inn have an option to leave at night. But yes it needs tons of new scripts for NPC not to be there, cinematic dialogues, quests etc...probably way to late for Larian to change this.
Crazy that BG2 was able to pull it off convincingly 20 years ago. Even the passage of time had consequences on quests (some quests even can cause party members to leave permanently if you don’t do it soon enough).
Not having this feels very Larian... clocks are non existent in their worlds