<<Profiles in Magic, Volume 5 mentions the notes of Rietyl Thumai (Nameless One) but references him as a monk of the Crystal Hand.

I think you're misreading that reference?

"We were lucky in finding several diaries of those days, including the notes of Rietyl Thumai, one of Jares Braun's advisors, and a student pledged to the ways of the Crystal Hand. It is this last collection that we delve into in this Profile book, specifically examining that young Monk's meeting with the fourth signatory of the Lunar Accord, Mizuhari of the Crystal Hand."

I understand that to mean they found several diaries and go on to list 3 separate examples of them. One was Rietyl's, a second one was the diary of an advisor to Braun, and the third diary was of a student of the monks (later named as Bashila.) They then go on to talk about the monk's diary specifically, not Rietyl's.