I just used Whirlwind Sprint's 3 word version for the first time and I can't shake the feeling that the last word "kest" is not even pronounced

It's like the voice actor was either about to sneeze or cough when pronouncing it

I heard it as a male Nord, though. Are the female ones any different?

It's true of most the dragonshouts

The latter 2 words are pronounced increasingly close together.

"Fus"
"Fus, ro"
"Fus, ro-da"

For example. Although when a female khajiit does fus-ro-da "fus" sounds like a kitten sneeze