I guess you could argue that using ð and þ like OP does makes English spelling clearer.
Right now, the digraph TH can make two different sounds (the sound in thy and the sound in thigh), and if a reader comes across a word or name they don’t know (like Athena or Mathers), there’s no way for them to know which TH sound it uses.
Using ð for the thy sound and þ for the thigh sound (which is what OP is doing) makes it clearer.
The point is that spelling and pronunciation in English are basically so different they might as well be two completely different languages so why bother with that one thing in particular?
I guess you could argue that using ð and þ like OP does makes English spelling clearer.
Right now, the digraph TH can make two different sounds (the sound in thy and the sound in thigh), and if a reader comes across a word or name they don’t know (like Athena or Mathers), there’s no way for them to know which TH sound it uses.
Using ð for the thy sound and þ for the thigh sound (which is what OP is doing) makes it clearer.
But how does that fix the other 99% of English spelling that is equally broken?
Why would it need to fix everything else? How could a single digraph swap fix any other issue than the one it is trying to address?
The point is that spelling and pronunciation in English are basically so different they might as well be two completely different languages so why bother with that one thing in particular?
Progress starts with small incremental steps? You could say this about almost any endeavor. At least someone is trying.