This is my approach, as well. I can usually glean enough information from other context clues to understand what's going on without fully understanding a specific word or phrase.

I tend to look up obscure English words that I'm not familiar with, more than a word or phrase in a foreign language that I don't know simply by not being a native speaker of the language. I like learning new words that I could potentially add to my vocabulary, but I'm less enthusiastic about learning bits of a foreign language that I'll likely never encounter irl.

I'm currently re-reading the Millennium trilogy by Stieg Larsson, and there's quite a bit of Swedish sprinkled throughout the story. For the most part though, they'll be businesses, streets or city districts. I don't really need to know exactly what/where "Gotgatsbacken" is to know its just a section of the city the character currently happens to be in. If it comes up more frequently, and seems to hold weight in the plot, I'll look it up.