@serpentilewitch actually, it's common and basic courtesy in the scans field to do so. It's not because Cafe Scans owns the rights or anything, cause as you said, it is a fan translation on both ends.
However, like I said, it's basic etiquette to do so. It's been less than 6 months since Cafe Scan's last release on GB, there's no announcement anywhere that they've dropped the series. Galaxy Scans is sniping the series.
How would you feel if you and other people had put in work for the chapter only to have another group just upload it, invalidating your efforts and those of your teammates?