Ayra

it's usable since she procs regnal Astra on every combat, she's also a bit tankier

Of course it is! I mean even -spd +res is usable, she is just too good. Train her up and see for yourself.
Wether try to get a better copy or not is up to you.Personally, I would save orbs for units that will fill holes in my horse\flier\armor\dragon team ( pick whatever you need)