I was going to mention the acetone myself as I’ve used it to remove miss-glued stuff. It works, but in my case it did soften the gypsum some and damage the paint, but as it was already damn neigh destroyed it didn’t matter really.
The thing that works the best for me takes a bit of modeling skill and obviously requires painting, but generally leaves me with a damn near unseeable fix, as long as we are talking about a slightly offset piece, I do the same thing to make noticeable cracks left over after reglueing, disappear.
I take a sharp exacto blade and usually some sandpaper, and basically dig a channel into the piece where the pieces meet. Obviously as small as possible to hide the difference in the pieces. Then I fill with apoxy sculpt to get a nice continuous join between the pieces and sculpt it to match. It works really well, but I only do it to basically destroyed items.
They totally do, at least I know super glue and a couple of others do. The only issue is often the dissolver will damage the paint or even the gypsum. :/ No doubt it’s one of those, item by item things as to if it’s worth it or not. I’ve had decent luck, but I always do it with crossed fingers knowing I could actually destroy what I’m trying to fix.