The Utena: After the Revolution manga is, as expected, kinda meh.
All it has to say is “Hey, it’s the anniversary of Utena. Remember Utena? Here are the characters you love, and they’re talking and maybe doing some familiar stuff. Ooooh.”
It adds basically nothing meaningful to the Utena canon. It’s 20 years later, everyone is an adult, but basically they are still the same people they were in school. The end.