When correcting/deleting Plot Keywords, the first time I click "Check these updates", it just reloads the page. I have to click it a second time for the correction to be highlighted in green and the "Submit these updates" button to appear.
I have noticed this, though only for deletes. I would expect the box to turn green after the first step -- even though it is often advisable to enter an explanation when deleting, in which case you need two steps anyway.
Almost every item in the Update system needs at least two steps: the first one to open the Item so it can be Added, Changed or Deleted. Then the data is added or changed. In the case of most Deletes, an explanation is required. Only after the data (or explanation) is entered is the item ready to be submitted.
The Keyword Delete is the only item I know that does not actually need something entered before submission.
For that reason, I expect that on that first click the system just 'unlocks' the item and returns the update-able version without any other testing. I doubt very much that this will change, since apparently the only time that the second click would be 'unnecessary' is if the update is for Keyword Deletes only. In any other case, the Submit button would not appear until after the other items were modified and the second click made. Modifying the procedure to 'correct' such a minor inconvenience seems to me a waste of resources better used elsewhere.