This isn't a bug, it's just an oversight from Larian because they probably didn't expect anyone to go through the game this way. Though they should definitely make it so that Raphael translates Astarion's scars at camp after you take care of the orthon, regardless of whether or not Astarion spoke to him outside of the mausoleum.
That would the best solution.
The thing though, is that OP deliberately wanted to avoid Raphael translating the scars so the ritual can be unlocked by the Necromancy of Thay in act 3.
