You cannot insulate scientists making errors in good faith from any kind of liability, if you make the wilful frauds liable. Because there is no 100% way of distinguishing the two.
You don't need to be 100%. We assume innocent until proven guilty in other contexts. At least some criminals are known to go free because we cannot prove beyond a shadow of a doubt they really did it. However we get a lot of them. It isn't perfect, but it is a standard.
Despite innocent until proven guilty, there are innocent people in prison or on death row. I doubt that is a standard that any scientist would agree to.
Scientists who publish research in a journal, and then it turns out that this research is wrong, for whatever reason, should not be held liable for the consequences of this.
Not that I'm in favor of the proposed measure, but saying because we can't identify wilful frauds 100% of the time then we can't protect the non-fraudsters, is just a bit silly, no? You have this kind of problem detecting any kind of fraud.
One test is, is there written communication between people about committing the fraud? If so, there you go.
There may be ambigious cases but there are non-ambiguous cases too.