Just make sure the seller owns the rights to the asset he’s selling you. Otherwise, the true owner can still sue your game… These are some of the know cases: link1 and link2.
Also recently I contacted the Marketplace creator of an asset I acquired from them and asked if I could have legal problems if I published a game with his asset. I asked the same question to Epic. Both replies didn’t state a clear ‘yes’ or ‘no’…