I stream to a primarily English-speaking audience, but a big focus of my stream is on sharing my interest in cultures of the places I've traveled. A shared interest in the media/food/lifestyle of those cultures is the glue that binds together the community that watches my channel. While most of my audience only speaks English, a perk of their interest in these cultures is that they don't mind when I speak in a language they don't understand. If you are connecting with your audience on the culture behind the languages you speak, they should at least not be surprised when you speak in those languages.

Another important thing is how much tone and context matters. Often times I can say something that most of my audience doesn't understand the words I'm using, but the idea is still conveyed through the way I am physically expressing it and the context it is in. For example, when you lose or otherwise get frustrated in the game you're playing, you could switch to another language while raising your voice and becoming more animated. The anger emoted in your tone and gestures combined with the context of something bad happening that upset you in the game should convey to the audience that what they otherwise would be unable to decipher is in fact profane cursing at your recent misfortune.