Would it be nice if error checking a bit lenient for vocab?

There is an option, but you MUST be honest with yourself when you use it.

There is a user script, [OBSOLETE] Wanikani Override ("ignore answer button") - #27 by bynars99, that allows you to mark things you miss as not incorrect so you can try again. If you legitimately know both readings, then use this to keep it from marking as incorrect.

But this can be seen as cheating. While cheating isn’t necesarily BAD, it is potentially bad for your learning. It’s easy to hit ESC all the time and never get anything wrong… but you don’t learn that way.

If you use that, remember you will need to install everything required for it. You can read about scripts here

Good luck!