Grand piano keys are individually weighted to balance the weight of the upper action / hammers. If you look at the locations of the lead weights in the keys, they probably correspond to which keys are staying up, and which are going down when you removed the upper action.
Whether the weights were installed correctly for an even touch is not at all a sure thing. But having keys that are unevenly weighted is not at all unusual. For now, I would suggest that you just work with the regulation of the action and learn about that. Later you can consider whether the piano needs re-weighting. If this topic gets going here, it tends to get very complicated and highly opinionated.
Another thought is that the key friction is not even, in that some keys might just not be moving freely enough. We can't tell this because these are static photos. If you move the keys, are they free enough to go back to the positions shown? Or do they stay up or down depending where you move them? If they settle back to the up or down positions shown, then it is the weighting. If they stay wherever you move them to, it is the friction.
Don Mannino RPT