I know it's not proper lore. But still, I will have fun resolving the problems. Maybe I'll surprise myself and explain away everything. :P
Bear in mind, I'm going with the non-canonical assumption that Revan kept the star forge. Though I suppose a light side Revan ending could fit too. At least a light side female (since you actually see Bastila for a light side male Revan in TSL)
Humor me my idea (I'd rather you rip it than ignore it, should I start a new thread?):
About the exile being exiled before the Jedi Civil War..... The exile started to once again regain her powers shortly thereafter. Her journey into the outer worlds was not as long as we had thought. The council noticed this, and took her back in. They wiped her mind, perhaps out of fear or perhaps out of mercy: they didn't want her to suffer the pain of her memories at Malachor. Most likely both. Her suppressed memory kept the echos from emanating from her.
As for Bastila being young... do we have solid facts about her age? Or was she led to believe otherwise?
Again, The exile, fought in the Mandalorian Wars, but as Bastila her mind was wiped by the jedi council out of fear or maybe mercy. The exile was then known as Bastila during the Jedi civil war. She was trained very narrowly so as to preserve her to the jedi code. Her strong ability to connect to others through the force allowed her to master battle meditation at a very quick rate. The council tried to stunt the other gifts from manifesting. Notice that her power increased extremely rapidly in the weeks she was captured by Malak. It's almost like she regained her powers at the rate that Revan regain his/her power after being mind wiped by the jedi council. So, the exile would then have lost her powers a second time. First at Malachor V, then at the star forge when she kept herself from being consumed by the overwhelming dark side energies of the star forge. She did this by disconnecting from the force once again.
I'll just re-iterate what I said before. Why should the padawon Bastila force bond with Revan to touch Revan's memories? If I were a Master Vrook, there is no way I'd ever let Bastila be the one chosen to bond with Revan. It's too ricky. I'd pick someone else. This is all true unless the council didn't have a choice, in which case Bastila's bond happened naturally... a bond that happens naturally if she were indeed the exile that was close to Revan during the Mandalorian wars.