I think I've come up with a way for it to work. What do you think?
The alien race is a shapeshifting race that can only speak a local language if they change their look to look like a race of people on the planet. Then they can speak the language. But in order to change their look they have to...
I'm still brainstorming but I'd think they would have good relations with some but with certain prejudices towards things that are different, they will also run into problems with natives
The story is a Sci Fi/Fantasy crossover alien beings coming in contact with fantasy beings.
I do like the idea that Steerpike mentioned about using magic. That could be very useful with the idea I have for a wizard character.