I did it, I cleared Ether level 15.
It actually wasn't as difficult as my level 12 run which gave me nothing in terms of Resonium and Gears.

So it actually just boils down to Luck, you can always retry until you get kickasss Resonium gears.
Oh, and Astra isn't over rated at all, she is worth every single roll.
Yixuan has a special Gear that converts Assists into EN specials.