I made a video:
https://www.youtube.com/watch?v=gMwXqU4LVCc

with the configurator gui closed:
the undo combo brings back inserters how they were before removal.

with the configurator gui open:
the undo combo brings back inserters but not with the configuration they had before, but wih the configuration the gui is showing right now.

Do you have an inserter in your hand when you do this?
Does it happen when your hand is empty?
does it happen when you press undo while holding a blueprint, or blueprint book
Does it happen if you have any other item than those previously mentioned in your hand?

I actually tested myself...
Inserter: Does it wrong.
Empty: wrong
blueprint: Correct
Other item: wrong.

I'll have to look into things, but considering I set it on player places item specifically, pressing undo must trigger the same event, meaning even if I filter it specifically to ghost_type == hand.item_type, it'll still do it wrong if you're holding the item that undo restores.

I've been working on a fix.
In the next update, the hand positions are changed ONLY if you're holding the specific item used to create the inserter, or it's ghost.
However... if you are holding the item (or ghost) for an inserter that is restored by pressing undo, it still does it wrong... there is no specific check to see if an entity ghost was created by pressing the undo button.