Well, what about lowering entry requirements so it's not a newbie trap, and cutting the spellcasting/manifesting to < 10/10? Doesn't solve the Ur-Priest problem but then, if a DM allows homebrew classes, they can certainly disallow cheesy 1st party classes.

e.g.
2nd level casting/manifesting in one, 1st level in the others. Plus some clever wording to bypass the wacky feat tricks.

Progression maybe 7/10 for primary, 9/10 for secondary casting.

Also extend the class to 15 levels.