Hi again Demi, Yes, I consider them all mistakes in BrE, just as they are defined on the web site, except that 1 is used in AmE, where it is not a mistake. Re 6 & 7: many people incorrectly say "I would OF " instead of I would have.
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CJ
"If I would have known about the party, I would have gone to it."
Level of grammaticality=6 (10 being completely grammatical)
Only slightly less objectionable-sounding as "If I'd've known ...")