Aule does not need a diaeresis. SeS probably wanted one here to indicate that the final e isn't silent, considering the topic was about pronunciation.
(it's not really an umlaut in the sense of changing the sound of the vowel)
Quick check in my copy of the Sil: clearly Aulë, and even in capitals AULË in the chapter title of chapter 2 of the Quenta Silmarillion.Correct. I thought Tolkien used one, but I appear to be mistaken.
What I mean is that the diaeresis is not needed 'cause Aule sounds the same as Aulë. And there is no "diaeresis" in the Elvish writing systems.Correct. I thought Tolkien used one, but I appear to be mistaken.
In Tolkien's orthography the diaeresis marks a vowel "unsilent" (like final e in Aule), or marks vowels in "hiatus", like in the word coöperate.I don't recall having ever seen ë or Ë anywhere except in JRRT's writings. In which language is this special letter used? Is ë analog to é or è or ê in French