I might be wrong, but as far as I’m aware, you can’t ever “re-lock” or “un-unlock” things you’ve unlocked. So, if you’ve done your radicals, and unlocked some kanji, if you go and mess up a bunch of radicals, the kanji will be still be available.
Also, let’s say you’ve unlocked all of your level four radicals, kanji, and vocab. You then mess up almost everything you learned in level one. If you still get all of your level four stuff to guru, you’ll still unlock your level five stuff. You don’t hurt your overall unlock progress by getting older stuff wrong. It just makes it take longer to burn the old items you messed up, and it will make you see those items more often in your reviews.
I really don’t know, though. @Leebo probably can verify or refute this for you.
As for me, I don’t really worry about messing up too much. Simple mistakes make me mad, but for things I actually mess up, I just keep the mindset that that means I didn’t know it very well. It is better for me to see those items more often, review them more, and fix my mistakes.
WK isn’t about increasing your level. It’s about actually learning kanji. If you just do the lessons, eventually you’ll make less mistakes, and you’ll unlock more levels. Don’t sweat the small stuff.