The whole initial dash animation management thing is a very new concept to me. I kept wondering for years, since Brawl, why some players just seemed to be able to run in an shield so quickly. I never knew what was wrong, but it's not like you ever hear about this concept. I learned it better through Byleth, actually. He has the same initial dash duration as Zelda, but I find it a lot more noticeable with Zelda, probably because she lacks a tool to just retreat and from a distant (like Byleth's Fair or Bair).
I don't think people really understand where Zelda is bad, and it never had to do with her frame data...at least, not in her moveset. It goes deeper than that, and something as subtle as this. On the other hand, she has fairly decent buttons she can press, such as Dtilt & Jab, whereas Byleth just has a mediocre Jab.