I believe that Russia should've waited things out because its the open state of war that gives Ukraine enough diplomatic cover to push to its pre-2014 borders.

That's kind of a fair point I think but I don't think the Donbas would ever be able to join Russia in this timeline. Without Russian intervention, the separatists likely lose and the years that follow establish precedent for Russia control of Crimea but also for Ukrainian control over Donbas. I think it's a valid, if cynical, argument to say that Russia should've cashed out with Crimea instead of going all in to try to take Donbas, but it means leaving the separatist out to dry. I do kind of agree with it though, I guess it comes down to what happens to the separatists if Ukraine wins, and I've seen people say they'd be genocided but I don't really buy that, seems speculative and like propaganda.