However, the Replacement button for the specific unit simple does not work:
There is no slider to select how many reinforcements to send, so you can never hit the produce button.
Meanwhile it does seem to confuse just about every other new player this game is getting by simply existing. I guess a solid 3/4 of all "how do I reinforce?" question are based on user hitting that wrong button and ending up in broken UI!
Please give that button a function or just remove it for the time being.