English is my second language so I may be way off, but I disagree with almost all of this:
- That's not what a tautology is, and the issue with the "Personally... to me" is probably more that "personally" is typically followed by a verb such as "(I) think" to express that what follows is subjective. The "to me" makes it sound bumpy, because it replaces the verb.
- Using "English" for "English language proficiencies" is completely valid, IMHO, and replacing it with "grammar" changes the meaning of the phrase. There's more to language than grammar. I would say "poor" instead of "bad" though.
- Fair.
"Personally, I think poor English is a huge turn-off."
Or, if point 2 is really important to you:
"Personally, I think poor English skills are a huge turn-off."