This might just be me, but I’ve tested it and am able to replicate.
If during a review I add a new user synonym, it’ll make me answer both reading and meaning for the item again, even if I’ve already done them and gotten them correct.
There have been times where I get a reading correct, then get the meaning correct and I get the green indication that the item has moved up to guru or whatever, realize I want more flexibility in my answers for the item, so I open up the F menu and add a synonym, then the item is thrown back into the pool and I have to answer for the reading and meaning again.
It’d be cool if anyone could try to replicate this plox.
I figured it’s intentional, to give you the chance to answer with the synonym, which I think they imagine you are adding because you wanted to answer with it and weren’t able to before. But I don’t know if they’ve ever commented on it.
Actually, there’s a bug there. If you get a meaning wrong, then get it right on the next turn and add the previously wrong (or any?) answer as a synonym, the review progress resets, and the item will eventually flash a level-up at you as you complete its reviews… but if you check the item at the end of the review session, it’s still a failed item, as it should be.