I made a tiny vn in Godot with dialogue manager; here's what was a pain to program:

- nuanced ui behavior, like buttons that don't overlap characters, skipping text without animations bugging out
- complicated animations that needed godot's animation editor (godot's animation system is cool until it sucks)
- managing dialogue-controlled behavior like global flags without having planned it out in advance

It took me about 6 months but I did the art and music and effects myself. It's sobs.moe/bwb if you want to see the result.