This place looks a bit abandoned... But nevermind, these are the official forums, so it's the right place to ask!
My wife has fallen deeply into RtR and I'm watching over the shoulder, thinking about giving it a shot too. One question though that I couldn't find a definitive answer on the internet:
Can you get rid of the corruption if you try hard enough?
Some old answers from February of 2019 say that you can't (there's apparently some "permanent" part of it which can't be erased); however there are also news of changes in the mechanics and some people claim that they have successfully purged all of the unclean.
I also understand that it's not "meant" to be cleansed; that you're "supposed" to stay on perpetual defense, and the challenge is to find a setup that works for all eternity. But... that doesn't feel very satisfying to me.
So, with the rules of the game as they currently stand - is it possible (theoretically and/or practically) to get rid of the corruption in a map?