The current scripting comparison functions `$gt()`, `$gte()`, `$lt()` and `$lte()` operate on interger values only. This does not support things like date comparisons. See the discussion at https://community.metabrainz.org/t/how-set-date-to-minimum-of-recording-firstreleasedate-and-originaldate/585648 and https://community.metabrainz.org/t/feature-request-numeric-functions-min-and-max-in-picards-scripting-language/585669 for more information.