Hi Fabio,
I totally understand your desire to dig into the backend, however, it’s not something we’re currently set up to do. I can share this screenshot of the recurring event area for a new event http://d.pr/i/YYuk. It does assume some sort of regularity of recurrence, not just random dates. If you’ve got random dates, I would just enter them separately and give them a common name, category, or tag to connect them.
Does that help answer your question?
— Julie