Voynich Welsh Numerology

[stellar]

Hi stellar,

Sorry I could not understand your question. Anyway, I'll say in advance that I would be hardly able to answer it, because I'm not a specialist in the history of languages.  

If you mean calendar dates then different styles have been used throughout the course of time and different cultures, for example the modern Gregorian calendar dates back to late 16th century and was adopted in different time in different lands; e.g. in Russia it was implemented only after the October Revolution.

If a word has a date for 1588, how accurate is that?