My thoughts: Retro + spring -> the past and the season of spring -> maybe a name inspired by a deity from long ago that was associated with spring? https://en.wikipedia.org/wiki/Deities_and_personifications_of_seasons#Spring https://www.goddess-guide.com/spring-goddess.html

Another idea is naming it after a spring (as in water) nymph from Greek mythology: https://en.wikipedia.org/wiki/Pegaeae