If you want to imply there were more diverse GA WWII era JSA members, it is rough going without inventing all new characters and retroactively inserting them.
There is not much you can really work with, but there are some bellow:
The strongest move is to emphasize The Hawks as legit Egyptian, if you're already pulling from All-Star-Squad with Will Everett Amazing-Man, add females Danette Reilly & Liberty Belle, add The Whip/El Castigo (descendant Rodrigo Gaynor Suarez) Latino American, (Night)Wing Chinese American Wing How, Zatara the Magician (Italian/Romani), Tsunami Miya Shimada (Japanese American) and Legends has added Amaya Jiwe(who can also go by FlyingFox).
Is that all of them? LOL! Was everyone else white male? Who else can we add?
I'm sure in WWII these guys would have fought for their country, together they would make for a rough, but actually one of the more interesting and diverse teams. And they all already exist somewhat genuine to the era. Just put them in an adventure together!
If the world wonders
why haven't we seen them as a team? (And so as not to completley retcon the original JSA [and All-Stars]), make it a covert mission, these are minority heroes who wanted to help their country but found it difficult to do so publicly. Maybe have Liberty Belle as the recruiter and leader, you can call them the WWII era
Liberty League.
Also for more WWII era, Freedom Fighters now retroactively has The Ray and Black Condor.