Played the japanese version when it came out, didn't translate all of it, but I don't remember the parts that I did being particularly bad.The game opens on a H-scene with the fairy. The reason? "We're childhood friends and you promised to show me your penis once you're an adult!" Uh... ok I guess? Fantastic characterization guys. The dialogue is trash, it doesn't enhance the CGs at all.
Just replayed the 1st scene of the jp version with translators on. I can say with moderate to decent confidence that the scene was originally comedy, and is supposed to set up the fairy as comic relief. Only tool that didn't support that was Atlas, which was too incoherent to get anything useful from (not exactly surprising).
That being said, I played the untranslated version without translation for most of it (hooking trouble, ended up just using an image->text converter, so didn't bother if I didn't think it was needed). If you like the game, the japanese version with translators might be the way to go, but I still wouldn't really expect any better writing that your standard h-game (part of why I was fine skipping translating most of it).