Even if that means scores are only updated once everyone has confirmed.

allow players to undo the "done" feature, if others are still playing,.

similar to the implementation on Dice Hospital, where you can un-confirm.

Yes, an "Undo the Done" would be nice. For everyone except when all others are Done. In that case your Done cannot be undone.

This is really needed, especially for the lake one where you think you have something and then it fills things in differently. Or, like I just did...you click your lake tiles, and then OK the round, only to find that one of the lake tiles wasn't confirmed and it messed up by entire round...

@Joezg
I understand your point of view, but when playing real time, we often validate moves quite fast, then wait for the other players....... and think during that waiting time (what else to do ?)
When one realizes he played a suboptimal move, the inability to cancel and change their actions can be quite frustrating.
Especially when it's something like having forgotten to place a special tile.

The only thing needing a change in the way it currently work would be to only reveal other player maps after the next round starts, instead of after having confirmed your moves.
Which, anyway, doesn't change anything, since joining a game as spectator already lets you see other player's validated moves (is that even reported ? Guess I might have to create a ticket)