I don’t have a horse in the race regarding whether there’s a free do-over or not; I could go either way. I agree that mistakes should be more lenient on the english side than on the japanese; especially since someone might know a different correct english option for a word, that they haven’t added to their synonyms yet. The precedent for that sort of thing is already set by having the user synonyms function and I approve of it strongly.
What I would like however, is if my mistake is say, a simple rendaku error (like おりかみ instead of おりがみ) i would get a shaking screen and a notification saying “Rendaku!”. If I need more detailed advice, I should still have the option of going down to the detailed explanation, but if it gave me that simple hint I would jog the noggin and perhaps instantly recall the correct answer for the next try. I might also mess up again; thinking the rendaku was supposed to be elsewhere, like when it jumps to an unexpected mora in bigger words. Same for っ, it can go red for all I care, but instant feedback telling me “you sure you want a big つ there pal?” would get keep me more immersed in the fight. Perhaps there’s an analogy to context switching to be made here; i’d rather not interrupt the flow.