The evolution of P/F vs T/K raises important questions

[ololololo]

Most of medieval handwriting is very ambiguous and unless you know the language, you cannot read it. So, you cannot build transcription alphabet on ambiguous letter combinations.

The problem is that there is often no ambiguity in the definition of the symbols. Sometimes it is difficult to distinguish r from s, but it is possible to do so. The shape of the symbols is quite stable throughout the text: p is p everywhere, e is e everywhere, ch is ch everywhere...