It gives you the correct English pronunciation. The point isn't to make a perfect phonentic alphabet, it's to distinguish between the English word "mate" and th

It gives you the correct English pronunciation. The point isn't to make a perfect phonentic alphabet, it's to distinguish between the English word "mate" and the Spanish loan-word "maté" which have different pronunciations. And I don't think the distinction between eh and ay as you've laid out is very meaningful to a native English speaker. Depending on where you are those may be pronounced exactly the same.