That's because Rakuen Le Paradis is a very eclectic magazine. It includes everything from "mature" yuri -- not mature as in sex (though sometimes...), but more adult characters or themes -- to a screwy comedy by Kumeta Kouji (remember Sayonara Zetsubou Sensei?) who traditionally publishes in shounen magazines, to slow and sweet romances like 14-san no Koi, to funny short works, etc. Per Ooyasan, its ostensible unifying theme is "romance."
It's only "josei" because some sort of demographic label was needed for the magazine, I suppose. I guess that was the most "yeah, well, it's not JUMP" choice they can go with, which really shows the weakness of the system.
Incidentally, seinen is an even worse demographic to shoehorn things into because so many wildly different things would work under the "18 to 30 something men would read this" category. It's like, well, those people read almost *anything*, what does this cute stepsibling romance have in common with Berserk?