Awesome project! The story and gameplay reminds me of "Rhapsody a musical adventure", it reads like a child's fairy tale. The overworld and NPCs really makes this game cozy. Since I know this project was made in love2D make sure to post it on love2D subreddit people will really like it there and will bring some attention to both the game and the engine you're creating. (also consider sending it to the game from scratch youtube channel which covers game engines as well). On a techinical level this is really impressive and there are a lot of systems already in place that can be used to create a bigger project going forward.
One feedback I can give is to try to center the camera back to the player(at least to the one who's turn is active) when it's the player turn again, this isn't a issue on most battles but I had a bit of trouble with it on the boss battle where the camera goes to the back of the stage. Like I said before, this is overall a really cozy game and I'm excited to see more of it!