I mean, the man has a thick accent. But he is speaking coherent English, they're just playing up the joke by splicing his audio to make it truly incomprehensible.

The editing they do for Gerald to make his speech gibberish is quite good, but if you pay attention you can get snippets of completely coherent sentences, but they splice multiple segments of audio together to make it nonsense.

Personally, I can't wait to see what new hairstyle Caleb wants to try out.