Words beginning [a]

[Emma May Smith]

Complementary differences can be ornamental if ornaments are only applied in certain context, like in the beginning of lines and at the end of words.

That's certainly true, but the environments for [y] and [a] are dependent on following letters. [a] is typically found before [r, l, m, n, i] and [y] elsewhere. It's not a perfect distribution other factors undoubtedly complicate it, but I'm certain that it is a real thing.