Are you sure that's not region-specific? Usually bands want the record label assigned to a particular region which the particular website that is reviewing the album caters to. I wouldn't be too surprised if they had to self-release it in North America.
How did you acquire the album? I'm fairly certain the download is through Sister Jack Records, the physical is distributed via Cargo Records. As far as I'm aware, the album, so far, has only had a European release - you've even used the European release date. If Amazon and iTunes, too, used that release date, then it's probable that they didn't know the labels Sister Jack/Cargo, and filled the missing information with the band's name for the sake of it.
For what it's worth, the band's own site lists Sister Jack as the official label, and lists the price with the American dollar, despite being from Germany.