Which plaintext languages to try?

[nablator]

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?

I don't know what happened, linguistically, (nothing?) in what remained of the Byzantine empire until the fall of Constantinople in 1453. Ancient Greek became a lot more popular in Western Europe with the Renaissance (for reading, not writing) when many ancient texts were studied and translated, originating from Greece and Egypt (the Corpus Hermeticum). Before that in medieval Europe, Greek and Arabic were important, but only indirectly, because the Bible and many scientific texts were known only through translations from Greek and Arabic. Few scholars could read these languages, so they relied almost exclusively on Latin translations.