Which plaintext languages to try?

[nablator]

How would XV century ciphers encode numbers?

Roman numerals. For example: Zaninus-Conradinus (1424) letter 3: "equites ccc et pedites d" = "300 cavalry and 500 infantry".

Maybe there are exceptions but I don't know any in ciphers before 1450. Probably later in more advanced ciphers like Alberti?

In normal texts (not ciphered) they used both the modern Hindu-Arabic form and Roman numerals, often together.

BTW, there are several suspicious sequences, like " o l r " in f111v.18 and f115v.38.