The problem was that the "real time" wasn't quite part of Earth-2 stories in the 1960s, so no one gave Batman a kid until 1978, the rest of Infinity were not conceived until the 1980s. Then Crisis happened and the Infinitors got lumped in with the unaging Modern Age characters.
The original characters of Earth-2 (JSA, All-Star Squadron) were largely based on actual published stories that gave them a history to draw on. If we were to try that now the question is whether to make up 30+ years out of whole cloth or to restart as if 1986's Crisis was the last appearance of Earth-2 and all the heroes' lives since have been frozen?
Go with the "real time" since the 1930's based largely on published stuff only or treat it as some new Elseworlds where someone like Geoff Johns (or Grant Morrison or Scott Snyder ...) gets to make up 1986-2020 events that none of us have seen before.