If the returned JSA is from "an" Earth 2, there's no reason Diana shouldn't be part of the JSA.
However, if the JSA is from Prime Earth (as seems the case so far in Doomsday Clock), then I vote no. Diana has had enough tampering and upending of her origins without an additional wrinkle that turns everything on it's head AGAIN. The fact that Diana can't return to Themiscira "ever" and hasn't so far in her career means she would have been active throughout the last 80 years. That changes everything. Also, she came to Man's World because Steve crashed on the island and he's still young. So, again, no vote.
A JSA from Prime Earth either needs to not have Diana, OR have a Diana replacement. Miss America or Liberty Belle (somebody in the patriotic category) would be great, or else Hawkgirl. I prefer a bonafide golden age character IF there's a replacement, rather than some newly created character.