You are just wrong. There are dozens of ways for these two tags to coexist. Even if we take your point of view, the "multi-pen" tag includes toys as well so if a woman uses a toy as she has sex with MC, then there is only 1 guy, 1 harem and multiple penetrations at the same time.How is there a harem tag if there's multiple penetration? That's no longer a harem if you're sharing any of the girls and there's anyone else penetrating any of them, let alone multiple people.
But if you are new here and you don't know if this game is for you and this is one of your criteria, then don't worry. there have been no other guys involved and this doesn't seem likely to change.