I've been in a very similar situation (twice meanwhile, shame on me), I just had a larger pile of open reviews.
Same as you, I asked here for tips.
I found one tip particularly helpful:
Go for a very quick review through all your open cards. That initial review doesn't take long. The cards that you remember are a sure pass, so just after the first review you'll reduce your pile by maybe 10-20% (for me it was closer to 10%, I believe).
It's not much, but better than nothing.
I then started to re-study the pile of failed cards, while continue to do the review on the rest of the deck.
Since I'd known the cards before, re-learning took less than half of the time of the original study.
As for your grading issue, I'd rather fail cards that you can't generate from the keyword only. As far as I understand Anki's schedulling system, even pressing hard will schedule that card in ab bit less time than you had since you last passed it. That may still be too far out, isn't it?