It is interesting to note that since the Cathedral has been more or less consumed by the dark from Aldrich and that Rosaria is there now using it as a safe-heaven, is imprisoned, or was there when the place was corrupted the; that the two are related. This is pure speculation but the fact Rosaria is now in the area where area where a recently awoken, and likely very hungry, Aldrich left gives me a slight reason to believe that Rosaria's soul, which has connection to Gwynevere because of the transportable miracle, was an attractive snack and was possibly half eaten, as we know Aldrich to be one to do. My only explaination for the differnce in the the half eaten top of Aldrich, aka Gwyndolin, and Rosaria, is that Rosaria using the latent power of her presumable mother was able to recreate parts of her body and save her own life. This likely came at a cost of her own tongue as a creul joke on the fact her life was saved, and mother was known for (Princess's Guard Covenant rewards in DS 1), miracles. Why those like Kirk, Leonhard, and all the other Rosaria's Fingers were drawn to the persuit of giving Rosaria tongue's back or comforting her, I do not know.
This is my first more or less thought out Lore post so I would apprachiate any helpful comments or additions. Or just say its dumb, to each thier own