Yeah there is absolutely NOTHING in this game that required Unity.
There is nothing in this game that justified picking unity; AND NOT USING ANY OF THE VISUAL NOVEL SPECIFIC PLUGINS...
I get that there can be reasons to utilize Unity, like being more proficient in C# compared to Python (it's not like both of them are actually fairly easy, high level OO Languages...), or wanting to include more elaborate Game parts/ Minigames that would be difficult to create in RENPY.
That's kinda all the reasons there could be.
But I mean it was totally worth it, to deal with all the issues associated with Unity, and trying to hamstring a Visual novel into it (again without plugins mind you), because the turn based dungeon crawler side-content is
INTEGRAL for the project AND THERE TOTALLY AREN'T A FEW DOZEN FREE TO USE TURN BASED COMBAT/ RPG PLUGINS FOR RENPY. /s
Honestly, the best course of action would be to port it over and redo it properly from the ground up in RENPY.
Imagine not having to fuck around with Day/Nigh cycles, Rollback, Save Slots, Misc. Settings for VN's, Windowed Modes, Stability issues, Item management, being able to Rename Characters etc. all because you use the objectively better engine.
Not to mention that RENPY doesn't take a cut and afaik is completely free.