User blog comment:Curtis712120/Earth-3/@comment-28458080-20160623042720/@comment-2112031-20160623170259

Considering that Barry specifically looked up Central City on Supergirl's Earth in order to get help, I highly doubt that he wouldn't have tried to contact their resident Flash if they had one. Not to mention the fact that Supergirl has never heard of a the Flash at all, which she probably would have if he existed on her Earth.