Would int be to bad an idea for multiculteral holidays but to many may be to much for now. Lore wise the 4th I feel should be celebrated in paragon because of where its located but also I found this snippet where you can eiteher include or to those objecting to celebrateing the 4th in game as is and wish for something else can use https://cityofheroes.fandom.com/wiki/In-game_timeline
Paragon City, 4 July 1932: Statesman, Dark Watcher and Maiden Justice form the Freedom Phalanx.
ie an anniversary of this event that happens to fall on the same date as the 4th