One time I can think of - not that I'm defending it - is the epilogue script to LOI after the ending.
The script/voice says that Mathias fled to foreign lands etc renaming himself The Lord of the Vampires and King of the Knight, or something along those lines.
This definitely seemed to be tweaked for western audiences. The Japanese version's translation equated to something quite different. Perhaps that the translation staff felt westerners couldn't fully comprehend.
Well, okay. Yeah. You got me on that one.
I do also say that, like any good woolseyism, it definitely works and doesn't really break anything.
I'd say the most notable mistranslations in the series for me are in Symphony of the Night, which reaches full blown "they weren't even trying" in places, like the pointless Lord of the Rings stuff that plainly doesn't belong anywhere in the franchise. Simon's Quest is probably a silver medalist here, but it's often hard to tell what's actually a mistranslation and what's the game being deliberately abusive to you.
May the Graveyard Duck live ten thousand years.