Glasnost

You're probably right. Most viewers in the US probably don't worry about the accents; we realize they're actors, and their accents are one of the least important aspects of their acting because we won't recognize that they're not authentic. It's no different than the awful "American" accents we hear on European TV shows. 😀

Like what was already stated, there's more than enough non-American actors who don't really do a great job at the "American" accent. What's funny are people who complain about certain actors having terrible accents, when those actors are actually using their real accents.

Weirdly, I find that I don't mind this too much. In books it drives me crazy when authors use some version of Google Translate rather than actually consult a native and they botch what foreign characters are supposed to be saying. (Because that's on them.) In movies and shows, however, I genuinely don't mind. True, with "Russians" I sometimes have to replay their lines in order to understand what they were supposed to be saying (and then have myself a nice, long laugh), but mostly it's okay. I'm actually rather impressed by Callen's Russian, considering he doesn't seem to have spent a great deal of time there, despite the origins (and considering Chris O'Donnell also doesn't have a reason to speak it at all). Having said that, do I agree with you on it being funny AND difficult to understand for us natives? 100%, yes.

I also try to take into account how (almost purposely) unrealistic NCIS is in some aspects, and doesn't make an effort to take itself too seriously. The team's joint linguistic prowess being one of them. Hetty's life being the other. It's just satire at that point. So given how comically languages are treated even by the writers, I can't really find it in myself to be bothered when third-generation Americans with distant Lithuanian heritage are playing hardcore Russians. 😄