TRY AGAIN RODENT!!
I reckon the pronunciation of the YHWH is purely an accident of how european languages evolved.
Jerome said that some ignorant ones when reading the LXX pronounced the YHWH as 'pipi' as they thought the square hebrew letters to be greek ones. So we know manuscripts existed in his day with the letters.
In latin it was written IEHOVAH. Bearing in mind that V was pronounced as U it implies an approximation to EE-YAY-OO-AH.
As time went on some european scribes started writing 'I' as 'J' (Which is why germans pronounce J as Y.)
In England seventeenth century editions of Shakespeare use 'u' for 'v' showing the distinction between the two letters was not absolute as yet.
I conclude the modern english transliteration is wrong.
Yahweh, Yehwah, Ehaywah are probably nearer.
Thats my two bits of droppings for today.