Agreed, Mr. Cat sounds kind of weird and British-y instead of having that mix of Australian and American accents. I'm fine with Stumpy's voice though. I think Kaeloo's voice sounds better here than in the other dub.
Yeah, he also sounds way too polite and laid-back, if that makes sense. XD Also, that "Mix of Australian and American accent" thing is something I've been thinking about for a long time... James told me he doesn't really hear it, hmm... :/
I have mixed feelings about Stumpy's voice. I like that he sounds like an actual boy, but it sounds way too different from his French voice.
Yeah, Kaeloo's voice is deeper, more similar to her original voice and a bit less annoying than in the original English dub, through I still think it sounds similar to it. I like that, it's cool. ^^
For the accent part, I guess I only noticed it because in real life I have an American accent, watch American TV shows and am primarily surrounded by other people with American accents, so I guess I could spot a small difference. According to TV Tropes, I'm not the only one who noticed it. Also, about Mr. Cat's voice, you're right. It's too polite.