Some of you may recall this fascinating forum thread discussing the chronogram which Zelenka attached to Vide Domine ZWV 179 when he presented it to Telemann in 1728:"Is this a riddle?"
One of the main contributors to this was Alex Went. I've just come across an article 2016 in the Prague College CRIS (Centre for Research in Interdisciplinary Studies) bulletin, in which he expands upon his theory and does some great research into chronogram culture.
What becomes apparent is that Zelenka a.) was an expert practitioner of this highly tricky and somewhat arcane craft b.) may owe it to the chronogram-mad culture which was especially prevalent in his homeland of Bohemia during his lifetime.
It's more and more clear that our composer was broad in his intellectual abilities and interests. Surely, this was nurtured by an intellectual family background and a good education. I wish we could discover exactly where that was and what it involved (given that there is still no actual evidence of it being at the Jesuit colleges of Prague).
Like the chronograms themselves, Zelenka's life-story is like an intricate puzzle to be worked out, and to the intellectual enjoyment of the inquirer.