The choice of these roman characters can be excused simply for their aestheticism and result of an impossible number, see Nonroman numbers. The date system documentation can be found at the desamber page.
A simple API delivers Paradise and Traumae Dictionaeries, you may read more about the tools on the API page.
Uriel: Haec maxime' respicunt Michaelem. Michael est Angelas; qui illuminat gressus tuos. Et haec revelantur in virtute et veritate non Vi. Ehrivevnv, sy. Heriven, appears on the XXIIVV sigil. The acronym recalls a sentence from Uriel(VR) to Dee(△) regarding the "Aldaraia sive Soyga vocor".
The reason why this quote in particular has been picked to represent the Neon Hermetism remains unexplained.