Grammarly says, "Review for pronoun use"

The computer was probably picking up the "singular they", because everyone is grammatically a singular pronoun. According to strict grammar rules, everyone cannot agree with they; however, this is becoming more and more acceptable.  (You will still encounter criticism from the strictest of grammarians, though.)  Lewis's suggested substitute, people would get around that issue.

The day is quite quite informal; depending on what this writing is for, to make it sound more formal use the era or the period instead.

I am no expert on biblical history, but describing a period as when the judges ruled has an authoritarian ring to it, whereas when everyone did as they saw fit sounds like a period of openness and freedom.  There may be a contradiction here.

I think you are OK with everyone. The program may have incorrectly seen 'Hannah' as the antecedent. Substitute 'people' and see if you get the same error.

The Grammarly software also seems to pick up situations where the pronoun's antecedent does not clearly relate to the sentence subject. In this case, everyone cannot refer to Hannah. So the software flags it and asks you to make sure the context makes it clear who "everyone" refers to.

I hope this helps.