We’ve used a couple different vendors in this space and I was impressed with the overall anonymity preserving attempts. It’s not perfect (especially in free text fields where “this comment was translated from Dutch” when you have only one Dutch employee is a pretty fair “tell”).
Our current tool is Peakon and it’s by far my favorite HR tool (which, to be fair is almost a content-free sentence, but Peakon is quite good IME).
I have no reasonable way to reverse-engineer your score or your comments in general (I have some employees who sign theirs, preferring to put their name to their comments, which is fine by their choice).
The only real way to stop these issues is to be proactive, not reactive.