Unfortunately there is a limitation where one can only enter release dates that are in the past. This seems natural at first, but for the game Factorio that I moderate, it has been in early access for a long time and the release date is now known to be the 14.08.2020. So I'd like to enter that.

Im am sure there are other game in EA that would appreciate that possibility as well

just use the date it went into early access? early access is basically a soft-release.

Well it should be really easy to remove the restriction on the website. I don't see any reason for a workaround here.

Can't you just wait until it's actually out and update the release date then?