The Günther Bible

Historically, the Ordensstaat actually used a dialect of Middle German in their chanceries. Why I'm not sure, because the lands of the Teutonic Order apparently didn't use it as a vernacular; IRL, after the secularization of the State into Ducal and Royal Prussia, the Teutonic Kanzelrei was completely abandoned in favor of the Low German spoken in daily life.

In Andalusada, of course, the Monastic State isn't secularized; it's overthrown. Monastic Middle German wasn't abandoned ITTL so much as consciously supplanted by the language of the rising urban population, and the Günther Bible (by establishing their Low German as a written language) was instrumental in doing this.

The Günther Bible itself

There were, of course, other German Bibles (High and Low) before the Günther Bible. Most of them were translations of the Vulgate, and the few translations from the original texts were manuscripts. When Günther produced his own New Testament, it was the first that combined Greek scholarship with printing presses. The combination was historic.

The original text used for the Günther Bible, incidentally, was a copy of the Opus Transtulit of Poszony. (Which reminds me; because there's no Erasmus, and because Hungarian-Constantinopolitan relationships are somewhat closer if one fateful marriage is any indicator, the Hungarian *Renaissance - and the Renaissance more generally - merits some rewriting.)

The Günther Bible's canon

• "Deuterocanon:" Günther used "deuterocanon" to describe Greek (and Latin) interpolations to the Hebrew Old Testament; his approach to them varied over the course of his life and different editions of the Günther Bible. Ultimately, he had two standard approaches:
• Earlier versions of the Günther Bible simply moved the passages to the Addenda (see below.) This is the more common approach, because it's less demanding for printers than the second...
• Later printings kept the deuterocanon where it was, but clearly distinguished by the layout and typography. (The last approved version of the Günther Bible was printed by the University of Revall, and went so far as to leave the deuterocanon untranslated.) This is understandably rarer, but remains common in academia and more conservative liturgical books. (The eight-book collection necessary to observe the modified Gonzalan Rite, for instance, is always printed in this way.)
• The Addenda: The entirely deuterocanonical works were generally disparaged as notha, and included in an appendix titled the Addenda ("things that must be left in.") However much he disparaged them, and eventually wrote prefaces on his objections to them, Günther never dared edit them out of the Bible completely.

The Günther Bible's impact

The Günther Bible established Pommersch as the Low German standard. (Previously, that standard was set by Lübeck, which took its eclipsing rather poorly. The Lübeck Bible, published later, split the Low German world between western and eastern orthographies, and gradually tilted the orthography of the free Low Countries away from the Brabantian norm.)

• More than that, the Günther Bible also firmly cemented Low German as a lingua franca in the Baltic for the next century. Only the rise of Denmark-Sweden in the 1600s was able to challenge that, and even then only around the Gulf of Bothnia. To this day, Low German has become the Güntherite equivalent of Yiddish: not necessarily a first language, but one worth learning to assert a common ethnoreligious heritage. 
• Because its Catholic, High German counterpart was translated independently, the Günther Bible drove a wedge between the two languages that was expanded with time. Theological and linguistic differences aggravated each other; it would take a solid century, and the implosion of the Holy Roman Empire in the Hanseatic Wars, before anybody was able to conform the two Bibles to a single standard.

This has led to some slightly different naming conventions:

• We talk about the additions to Daniel as separate books; Andalusada's scholars talk about α-γ Daniel. (Esther gets a similar treatment; "α Esther" would be immediately understood there and draw a blank stare IRL.)

This is a work in progress. It will be expanded upon