Is it racist or okay to tell a person who doesn't speak English as their first language that they do speak good English?

At my school in California, we have quite a few non native people from various countries staying here for exchange programs, who know their native language and some English. You can tell they're trying hard to process and speak English as well as they can and I want to praise them for it. I just want the person I'm talking to know that they do speak English very well and I want to build their confidence in speaking a foreign language to native speakers but I don't want to insult them by assuming it would be hard for them to speak and understand English in the first place. I remember when I was learning my second language around native speakers, I liked it when they said I spoke their language good because it gave me confidence to speak to them more in their language. But is it different to tell other people who didn't speak English as their first language that they do speak good English?

*I really don't want to offend anyone, but I want them to know they're doing well.

Please, if the answers can mostly be from people who don't speak English as a first language, that'd be great but other opinions are welcome too.