Given their experience in the game development industry, yes, I'd say they know what they're doing, are they having teething trouble with Unreal? For sure. Career mode didn't break for everyone, it has broken for a lot of people yes, appears to be because of CER being inserted into the career, I'm lucky, it didn't affect mine. CM are on it as you would expect, will we get a hotfix? Who knows, worst case people need to restart career mode, not ideal, but could just be the unfortunate by-product of releasing the new rally into existing saves.
The stuttering seems to be affecting PS5 more than Xbox in terms of consoles, most of the comments I have seen around stutters still being there or being worse are all PS5 user, I've played a good number of hours on the new update now on Xbox and the stuttering is a non issue now on Xbox, occasional screen tearing but nothing terrible.
If you have any trial left, give it a go.