Actually they didn't, E2 Donna's origins is actually the simplest of things:
-Steppenwolf and Diana sired Donna
-Steppenwolf made off with Donna and raised her
-Donna remains evil, technically loyal to Darkseid before Steppenwolf
-Right up to when Earth-2 is destroyed and she falls back on her Amazon background and becomes good.
Not to mention she was actually pretty competent both as a fighter and as a leader.
So I would have been fine if DC had just ditched the Finch origins and have E2 Donna boomtube over to E1 and get stuck here.
I meant Donna Troy as a whole, not just this particular Donna Troy. Which in addition to the existing mess now has "... and then there was Earth 2.3 Donna who was Diana's daughter with Steppenwolf and is more or less unrelated to any other donna Troy" mudding things up even more.