I'm going to be reading through the Dragon Language section of the Prima Official Game Guide for Skyrim for any possible words we're missing, or to gleam some more grammatical rules from their translations.  I'll be posting any of my findings here.  If you also have the guide, you're welcome to follow along and post additional speculation (if you don't have the guide, feel free to comment as well).

"The Dragon alphabet consists of 34 distinct runic symbols.  While most have direct English-letter equivalents, some represent sounds English uses two letters to represent, such as "th" and "ch".

This is under the "Dragon Alphabet" section.  We know for sure there are 34 letters.  It might just be how it's worded, but it seems to imply there are also letters for "th" and "ch".  Otherwise I think it's just using "th" and "ch" as examples for two letters in English that form a single sound.

I'd be more inclined to believe the latter, but there is the enigmatic mystery of this letter found in the Dragon font ripped from the game itself:

0

This letter does not appear on any alphabet tables, and so far is a mystery as to what it means.  Could this be "th"/"ch"?

Reading through the Word Wall translations, I think the suffix "-nu" could mean "-less", as in "faasnu" ("fearless").

"Vegunthar wahlaan qethsegol bormahii vahrukt, Hungunthar Tiid-Naak, kriaan se junnesejer, kroniid se Dunkreath.

Literally: Vegunthar built (this) stone (in) his father's memory, Hungunthar Time-Eater, slayer of the Kings of the East, conqueror of Dunkreath.

More liberally translated: Vegunthar raised this stone in memory of his father, Hungunthar Time-Stealer, who slew the Eastern Kings and won for himself all of Dunkreath."

p.647

I'm glad they offered the secondary translation, because as we know, "kriid" means "slayer", and "kriaan" means "has/have/had killed".  Interestingly, "Naak" is used here to potentially mean "Stealer".  Also note the use of "se" instead of "do" in the last sentence.  "Se" is typically only used to form compound words ("junnesejer").

A more accurate translation might look like this:

Vegunthar raised this stone in memory of his father, Hungunthar Time-Eater, who had killed the Kings of the East, and was conqueror of Dunkreath.

"Nonvul Bron, dahmaan daar rok[sic] do fin Fodiiz Bormah - Oblivion loost nid Nah med spaan vahdin beyn.

Noble Nords, remember these words of the Hoar Father - Oblivion hath no fury like a shield maiden scorned."

p.647

What caught me off guard here was the use of the word "Oblivion".  It's not just the translation, it's written on the Word Wall too (you can see it here, the first word of the third line).

This then turns into an etymology debate: is "Oblivion" the Cyrodiilic name, or is it the name that every culture refers to it as?  Since Dragons were the first non-Aedra to exist and have language, it could be argued that they devised the word "Oblivion", and it has carried down to every other language since.  Or, this could just be an oversight on Bethesda's part (but this brings up another messy debate of how we define canon, if we're allowed to make that sort of discretion, etc.)

Yeah, it could possibly just be a short-cut of bethesda's but I think I prefer the idea that that word was passed down to mankind during their enslavement under Alduin. If you think of it, if they were the first language then they would hold a lot of sway on the language of mankind.

We have a non-canon word right now for "Oblivion", "Uradiin".  Opinions on what we should do with it?  We could delete it, or replace it with "Oblivion" in case people search for a translation.

Oblivion is the literal translation right, and that's what the letters spell? If so then I believe we should honor that.