I find it funny too, but I don't think it's racist tbh. A bit rude if you laugh in their face, but I wouldn't be mad if people laughed at me for speaking their language wrong. But then I guess it also depends on WHY you're laughing. Like are you laughing and suggesting that their stupid, or are you laughing because it's genuinely funny/cute? I've seen people laugh at foreigners trying to speak English before and call them idiots. That's not cool. But if it's just playful, I think it's ok. It might also be nice if you helped them understand how to correct what they were trying to say after laughing.
Also, language is something that you can change. You can practice and get better at it until you speak it fluently. Your race is not something you can change, and that's why making fun of someone for being a certain race is racist. Because they were born that way and there's nothing anyone can do to change that. Not the same with language.
