I've watched some minutes of those movies and I'd say there are real creampies... For example at the last creampie of HND-511 the guy is at least fucking her for 1:30 without cuts. And you can see there's a moment where he wants to jizz but he can't. That's not something you usually see in fake creampies. When it's faked everything looks super simple. Cut, 1 minute fucking and the actor doesn't struggle at all to cum. They can't extend that take because the "cream" would spill over and ruin the scene.
Or maybe their technique is wayyyyy better than in other studios.