Which plaintext languages to try?

[oshfdk]

Thank you for the answer!

What about Greek and Arabic, were they used in parts of Europe at that time?

Last time I checked Greece is/was in Europe.

Yes, but I was thinking more in terms of how popular Greek was for creating manuscripts. I was under impression that Greece for the most of the 13-15th centuries was occupied by various fractions until falling under Ottoman Empire later on. On the other hand I vaguely remember Kircher using Greek sometimes?

Not much remained of Al-Andalus until the 15th century, in the south of Spain.

So, probably Arabic is not very likely, which simplifies things a bit.