Based on Kanata's dialogue, we can assume that they did meet Kanata, as Yamanashi Ganma of course, off-screen on ep 4 season 1. Saori asked which artist Kirino wanted to meet, and Yamanashi Ganma is one of them.
Kanata never appeared on that episode (and maybe she was wearing disguise there so Kirino and Kyousuke didn't realize it was her on current episode) but I think the booth where
Kyousuke is shocked reading Meruru doujin on booth that has a maid, is Kanata's booth.