<<Excuse my ignorance: What is really the problem with typing g, then y, for achieving ‘gy’? Is there a semantic difference? How would a gy digraph be different?>>
Since this is my first adventure into designing a typeface, I want to be sure I’m doing things correctly for as many European languages as possible. My Polish fellow designer friend would never forgive me if I don’t get the kreska right 
So I’m diving in a bit deeper. I only speak broken French, and I certainly don’t extend to Hungarian, Slovak, or Dutch. My confusion comes from seeing glyphs for dz and ij but not gy. But if this is not a problem with Hungarians, then I’m satisfied and will let it go.
Thanks for all the support and the book recommendation! I’m ordering it now.
Learning. Always learning . . .