Why and how the text could be Bavarian

[JoJo_Jost]

If we take this approach as a starting point, then all other medieval language candidates — Latin, Spanish, French, early Italian, Middle English, Middle Czech, Middle Hungarian, Middle Bulgarian, Middle Romanian, Old Catalan, Old Occitan, Old Frisian, and Hebrew — fail on at least one of the following criteria: high article-like frequency (19%), frequent prepositional elements (14%), productive verb prefixes (4%), a common coordinating conjunction (3%), an average word length of about five characters, and a strong underrepresentation of 2–3-letter tokens. Only Dutch and other Germanic languages come close — but Bavarian, with its characteristic word shortening, provides the tightest fit. 

But of course we don't know how the cipher, if it is one, really works....