[losvedir]

I mean, I wouldn't expect problems if the thing were called "Buttercup" would you? Or what about "Button"? "Saturday" (which has "turd" in it)? Are there problems with a Harpoon ("poon") IPA?

Clearly the presence of a sequence of four silly letters isn't in and of itself disqualifying. Native speakers often won't even register the juvenile bit inside it.

My only surprise here is that "scuttlebutt" doesn't work that way for other native speakers. It must be just my dialect or circles then, because it's an ordinary word for me which subsumes the "butt" within it (like I'm certain "button" does for you). But I guess it's not universally like that and the word is odd or rare enough that it doesn't do the same for others.

[corobo]

The butt is more noticeable because it's at the end of the word as a standalone syllable.

With your examples the butt sounds are mixed in so they don't stand out as much.