Yup ... just got +1 Cha ... and it worked. ^_^
Now my sorcere have 20 Charisma on level 4 ... not bad. :3
You jut need to let her take Marina, if you pick anything else, she would just give you Str ...
But since your pick the stat AFTER conversation, i dare to presume its a bug.
Just noticed when i was cleaning my bags, i got also Strength one.