The Monstrodome Text stands out from the other languages of the spiral because it's not specifically found in any world-- in fact, it's only found in the Monstrodome book itself, which is simply a housing item. I honestly stumbled across the text when touring a couple of houses, and I realized that the symbols seemed to be arranged in a way that looked like sentences:
Unfortunately for me, the Monstrodome only shows 2 pages in the entire book that display the mechanics of a duel circle. Additionally, the text on the right page is simply mirrored from the left page, so only half of it is legible and meaningful. What I found interesting about this text is how it actually uses existing letters or accents from Greek and Latin alphabets; there is even one symbol resembling a combined d and 3 that's used in phonetics. It was tempting to just assume that the symbols that looked like e's were actually E or that the lambda symbols were actually L's, however, it didn't match up at all. Instead, the Monstrodome Text is your classic cryptogram.
Message on the top of the left page
Message on the bottom of the left page
Given that the Monstrodome is all about collecting monsters with duel circles, you would think that the messages would have something to do with that, right? Well, I guess KingsIsle decided to ditch the lore options and instead write some funny lines like the Dwarf messages. There's nothing like staring at a mysterious cryptogram for and spending an hour deciphering it only to find some memes. I guess this is modern day archaeology. Anyways, the Monstrodome Text symbols were easy to compile since they already existed in other alphabets, so down below is the nearly completed translation table. Honestly, I think that this text has a lot of potential, and I've been scouring other Monstrology-related decorations to see if I can complete the alphabet.