Seems like such variants on the “Age” expression would be a good expansion for the Date Calculator. (Doug notes that this gramplet uses the same date parser as other plugins.)
Then the form could leverage that with a Birth date “calculated” guess (if missing) when enter Census data.
A while back (2021), I submitted a Feature Enhancement request revised labels for that gramplet to give clues during data entry. I wasn’t confident enough to submit a PR and the addon owner (@dsblank ) was taking a sabatical from Gramps. So that request is marooned.