This got particularly bad when we realized that our kid's school was not teaching phonetics, but that the special tutor we hired was running a basic phonetics routine. And that that is really just 44 flashcards for them to work through.
To your point, Spanish generally has 24 phonemes. This is why they can map it to the 26 letters much more straight forwardly. Though, I'm a touch surprised it can map to German so easily, they have more phonemes than English, if I'm not mistaken.
All of that is to say, I'm glad you found the discussion interesting! Apologies if my pet peeve came on too strong. :D
I am curious, btw, I don't understand what you mean about "yesterday" sounding like either "today" or "Friday" The "day" on both of those sounds the same to me?