Other recommendations: make that you can store negative trait that are part of a recipe. I have the Bitchy trait and it's annoying that I can't store it for when I get all the other ingredients.
Add an indicator when you pick a trait if the trait is in storage. it would help when you are randomly stealing traits to complete the traits library.
Add a way to find the location of the NPC (maybe at a cost). Some of the NPCs are very elusive, so it's hard to raise their relationship
When you summon an NPC to your house, make the trade option and the trait selling (+the option to buy trait storage). It's linked to the above problem, since NPCs are hard to find, it's easier to just summon them once they become friends. But some options aren't available when summoned.
Add the trait given by the tomes. Some of the book titles are confusing (I bought one thinking it would give me muscular or lean but it gave me masculine flat chest)
Bug: if you summon an NPC to your house then make them leave, you can resummon them and the daily intraction will be reset.