I think it would be a lot more interesting if Raphael had more options to tempt party members.
My suggestions:
Trade the Crown of Karsus for a heart for Karlach.
Offer to help Halsin solve the shadow curse.
Help Shadowheart remember who she is / find her parents.
Help Gale with his magic consumption issues.
Offer to actually remove the parties tadpoles immediately in act 3 for the Crown.
Things like that, I think at the moment Raphael is too easy to turn down for Tav and other party members, with only Astarion and Lae'zel actually wanting something from him.
