Using yodelling to express mocking

I think an English ear would interpret the yodelling literally, to comical effect.

A better translation might be something like "sneered" or "scoffed".

I've only seen "yodelling" used to refer to a specific way of singing. Words I would use are "jeered" or "scoffed". You could also say "he remarked mockingly".

If this use of "yodeling" means that the speaker's voice is varying in pitch, then a good parallel in English would be "singsong voice". A common (though considered immature) form of mocking is to repeat the target's words as if you were singing a nursery rhyme.

You could replace "yodeled" with "said in a singsong voice", or even "jeered/sneered/scoffed in a singsong voice" for extra color (as per the other suggestions).