A single enemy model has no targeting restrictions whatsoever. What in the game is not a single enemy model? Targeting restrictions are UNITS. It is the most basic concept of shooting. P. 39. The very first sentence.
"A model can shoot at an unengaged enemy
unit..." (emphasis added)
The spells say you can target:
"a single enemy
model" (emphasis added)
That is where it overrides it. A model is anything in the game (including a character in a unit, including a bannerman in a unit, including a musician in a unit, including the 4th goblin in the 3rd row in a unit).