I don't know if I would change anything at this point, but on the trip to Japan it would be interesting if it was Himari who invited the protagonist to spend time in Japan because of the debt and there he met her family,
If they're listening to feedback, I don't see why they couldn't add that in later on as an alternative was of getting to the Japan content. It would be hilarious to see the reactions of whoever goes with you if it triggers after Himari recognizes you as her Heavenly Husband, especially Anna (depending on her route).