-Nor suffix from "Naur"

Thank you! That explains it. I found the sidebar in the Names section that goes through all the rules. I knew it didn’t look right, but wasn’t sure why. Sammath Naur was the only name I could think of where the word root wasn’t modified. I do however have a follow-up question just to clarify that I understand the AU change.

The AU -> O change is only certain in the end of the word? If the compound is present in the beginning or middle of a compound word, it is treated differently based on the specific word. So the history of the original word being a long or short “A” determines whether AU changes to “A” (as in Narya) or “O” (in Glorfindel) depends on how the original root word was meant to sound? (naur from naro being long, and glaur from glawar being short?)

“Glarfindel” certainly doesn’t sound right, nor would “Norya”! I guess each time a word in question has the AU compound it needs to be interrogated to make sure it reflects its original sound as closely as possible.