Months names are all one off?

[Jorge_Stolfi]

If we are talking about the  marginalia on the vms zodiac illustrations, then i do not see the problem.
Zodiac signs are spread over 2 months, the Start month and the End month.
If you are only going to assign 1 month to each sign you need to choose either Start or End month.
Vms astrology marginalia person chose End month.

Yes, and that is indeed the month that contains the largest part of the sign's period as it is defined today.  But whoever wrote those month names could have used that rule only after the Medieval convention of "one sign = one month"  was abandoned in favor of the 'astronomically correct' convention astrologers use today, namely "one sign = one 30 degree sector counting from the equinox".