During my first watch-through of the HBO miniseries Chernobyl I found the actors' accents jarring. It's not that they're speaking English with Russian accents that are hard to understand; it's that they're not speaking with Russian accents. They're speaking with British and Irish accents. It's like
watching Star Wars Game of Thrones! Plus, the senior party apparatchik in Pripyat is Maester Luwin from Winterfell.
In
the episode 1 podcast showrunner Craig Mazin explains his deliberate choice not to have the actors speak with Russian accents. He notes that even professional actors tend to "act the accent". He didn't want actors subconsciously hamming up a Russian stereotype, turning the show into a self parody a la "Boris and Natasha". Moreover, he explained, he wanted the actors to be able to convey emotions clearly with their voices. It's harder to do that when they're struggling to portray foreign accents.
Mazin still wanted it to sound foreign to US audiences, though. He cast primarily English, Scottish, and Irish actors. By the third episode their accents stopped breaking me out of the moment... except for the few additional times actors used British idioms.