The existing elven heads are pretty...I wouldn't debate that... but there's nothing to distinguish them from half elven or human heads aside from ear shape. You could put all of the elven, human, and half-elf heads into the same pool and nobody would be able to tell which is which. Some minor changes, particularly to eye size and shape would go a long way towards making elven faces not interchangeable with half elves.
Maybe Female Elf heads 3 through 5, but 1 and 2 are god awful. 3 through 5 could use more angular look. Similarly, the male Elves look more like what would be male Half-Elves and vice versa (the male Half-Elves look like male Elves). Elves should have more angular faces which is what people have been arguing.