OK, I've submitted those two Radirgy CDs. They will be released first at the ARXIAL RENDEZVOUS 2 event this month on the 29th.
http://rs34.co.jp/event/180729/
They will be made available to purchase through their own webstore and other stores like ゲームショップ1983, BEEP and so on at some point after the event. Webstore may or may not include a bonus for those who purchase early.
EDIT: looks like these CDs will be released on the 29th regardless. Already available for preorder
here.