Retina, 24 18 17 16 bytes
1 byte saved based on an idea in MT0's answer.
\wf?k?
y
\byy
He
Explanation
\wf?k?
y
This simply turns all letters into y, but if they are followed by an f or k we immediately replace that as well. By removing f and k we "normalise" the lengths of the words so that they now all have two more ys than they need.
\byy
He
This turns the first two y of every word into He, completing the transformation.