The date is incorrect as reported for HMDA but you shouldn't go back and correct it now. Don't touch anything that has already been submitted.
If this is just an odd needle in your HMDA haystack maybe it won't even be found or at least it will viewed as just a single error. You need to worry about what HMDA examiners call 'pattern and practice'. If you consistently have application dates reported erroneously, then you're going to have a problem. But again, it's too late to fix what has been submitted unless you're make to do a resubmission by the examiners.
All that said, if your review now finds a pattern & practice, write it up and train like crazy so you can present that to the examiners. Being proactive is looked upon favorably during exams.