I still am sure that the Latin connection is at best a red herring. The speakers of that tongue throughout all the centuries before Comenius do not seem to have noticed that it had more than three - and in any case, Comenius does not indicate what forms of words these extra four genders had. What Comenius might have thought was less that Latin grammarians had been lax in their analyisis, and more that the Latin language was deficient in this respect, which is an opinion not widely shared. The angelic approach might be more fruitful, since we do know of seven archangels. - but then there is a tendency of people in a certain cultural area to describe things in sevens - see for example Geoffre Ashe's
The Ancient Wisdom. (wish he hadn't chosen that title!
). I suspect that the esoteric /astrological approach is the best; unfortunately I can't think of any concrete examples.