As otehrs have said, yes and no. Porn dialog's pretty awful, the biggest problem for us with Japanese-translated dialog is that we don't talk that way.

For example.. Here's a phrase you hear in porn a lot. "kimochi" or "kimochi ii"

Kimochi refers to having a feeling or sensation, and Kimochi ii means "I have a feeling that is good." or more specifically "I"m feeling a good thing.."

the 'american' porn equivalent is "fuck yeah.. yeah.. yeah.. yeah.."

but when translating.. well, it doesn't really make sense for sweet innocent Hisa-chan to yell "OH YEAH FUCK ME"... So it tends to be translated as "it feel so good... my body feels amazing.. I feel good.. it's so good! it's so good!"

and it's such a small simple phrase. Ki-mo-chi .. it's easy to say, it's easy to sigh out and moan out.. a lot of japanese words and phrasesa are a lot shorter than the english equivalent.. "Nakadashi" for example, means that dude is cumming inside his partner's body. it's .. 4 syllables. One word. That's all that's needed to say all that. while we'd need "I'm coming inside your pussy" or something that just sounds.... awkward and cumbersome. because who really says that? It's a mouthful, but there's no way to do it in english.

There;s also a lot of difference in how the two cultures expect females to act and speak in porn. a very passive female is traditionally attractive in Japan, while in america we want 'oh yeah fuck me.. uh huh.. fuck my little pussy" .. rahter than "ah.. it feels nice... wow.."