The letter ‘K’ as a mark of origin?

[Petrasti]

Please correct me if I'm wrong, but the fact is: the manuscript dates from the Middle Ages, between 1400 and 1430, and is of European origin based on the images, possibly from the region of Northern Italy because of the battlements. The scribe and language or cipher are unknown (these are the basics). Some letters correspond to the Latin letters a and o, while others are unknown. If there are a and o, q and y that we find in Latin, why shouldn't there be a t or k? Yes, of course, there's no definite equivalent; these are simply possibilities until the puzzle is solved. Nevertheless, the question remains: if we can identify letters, why shouldn't it be a k k or a t t? Or, what could the equivalent of C be?