That's fine. I still dread the personality section the most myself, and actually hit a fair bit of a roadblock with that in my SU - especially when I remembered I had to do four of them. Generally the way I do it is come up with a history and then sort of figure out what character traits that would inspire, but when said histories basically amount to 'birthday present', 'housepet' and 'store-bought' it turns out pretty tricky.
Anyway, would you count your SU as done? Though the personality section's a little short, as you said, the history section and RP sample are of high enough quality for it to be accepted now regardless.
Also it's 'Heracronite', not 'Heracrossite'