I'll save discussion of the story's literary merits to my review of all the nominees in this category; for now I want to indicate some areas for linguistic improvement, specifically in the use of Latin in the story. There are a number of slightly odd usages, and three that I spotted which are flat-out wrong. Going in reverse order as they appear:
- Towards the end of the story we are brought to a room called the "Cella Mundus", the chamber of the world. But "Cella" normally means a small room, and this one is very big; also, "Mundus" should be genitive "Mundi".
- The central character belongs to a body called the "Collegium Occludum", presumably the hidden college. There is no such word as "Occludum" in Latin; the writer should have written "Occlusum". (I see that Occludus is the name of the home planet of the Death Spectres in Warhammer 40k; perhaps this is the source of the confusion.) "Occlusus" is closer in meaning to "closed up" than to "hidden", but in fairness that may have been the intended meaning.
- The title itself, "Opera Vita Aeterna", is wrong. Though the phrase is not actually used in the story, it's fairly clear that it is intended to mean "The works of an eternal life". However, the long-lived protagonist completes only one work in the story, albeit a long one in many parts, so "Opera" should be "Opus". In addition, "Vita Aeterna" should be genitive (the same error as "Mundus" above), so that would be "Opus Vitæ Æternæ". Finally, of course, the use of "eternal" in this context to refer to a long-lived being in the world of the living jars as being rather different from its normal context in Church Latin to refer to the afterlife; it might have been better to choose another word entirely.
(I was also surprised to read that the monks in the story had three books of "approved apocrypha", surely an oxymoron.)
You can, of course, vote for the Hugos yourself by joining this year's Worldcon, Loncon 3, here.