Technical difficulty is the difficulty in making the piece sound the way you want it to sound. Musical difficulty is the difficulty in imagining the way you want it to sound in the first place.
While that definition might fit your idea, that doesn't seem to be how most people think of the terms.
For example: people will say, "Oh Chopins tristesse? Technically thats EASY. Musically though its way harder than Waterfall. But man Waterfall - that things much tehcnically harder than Tristesse."
See here?
Tristesse is NOT easy to make it to sound like how you want it to sound. It takes some time. However, hitting its notes isnt a problem. So by your definition it would be technically hard; which doesnt seem to be a view of people.
When people bring up technical difficulty, they often seem to mean "getting around the notes", i.e. hitting them accurately.
This is why the often insist that "ohh La Campanella is way harder than Chopin etudes" even though it might be harder to hit right, but not as hard to hit well.