Was Hartmann Schedel in possession of the VMS? I think so.

[Jorge_Stolfi]

And I'm afraid that's a damning verdict on the possibility of deciphering it. Because there are so many possible interpretations of a cipher that has encrypted the language phonetically, if you don't know the dialect exactly. It's like a jigsaw puzzle with about 12,000 pieces, many of which are just blank....

If it were indeed some Bavarian dialect, it would be easy to crack.  No matter how divergent and obscure, it would have the same basic Germanic structure, and many words would be very similar to any reference dialect.  See "des", "dass", "so", "wo", "wenns", "is" in the examples you gave.  Even if it was encrypted, as long as the encryption was one-to-one on words (as the statistics indicate), it would be possible to identify function words like those, and some common nouns like "herb"...

All the best, --stolfi