I don't know about this project, but in general, no, they won't go request a rescan. (Ancestry may not have possession of the film, the film might be damaged, the original documents may not exist anymore, the original documents themselves may be damaged or illegible, etc.) I want to say that has actually happened at least once, but WAP is not the top of the food chain and we typically have to cope with whatever quality comes through.
Based on the illegible sets I've seen so far, in both this group and the original project, I suspect the original films are either damaged or were done poorly in the first place (or both), so rescanning the film won't do much good-- what would need doing if that's the case is re-filming the original documents, if they even still exist.
If you reject a set because it's illegible, someone else will eventually still have to key it; when all else fails, there is a small pool of special volunteers who handle those, but it's best to do what one can when that's humanly possible when you have the time to do that, and reject the egregious ones.