Hello,
It's an interesting feature request indeed. Sadly, it completely break the privacy model of CryptPad, where everything is end-to-end encrypted.
As far as we know, neither the iCalendar, nor the CaldDav standards supports encryption. It would mean that your data is made readable by everyone who has access to the link and you'll loose complete control over who can access it.
We understand the need for people to connect CryptPad to other tools and are investigating API models that would allow integrations. However, I don't think it's something that will be doable in a short time-frame. We have yet no funding, nor time to work on this with our current roadmap.
Hope that helps clear some things up. Please don't hesitate to react and share ideas about the privacy side of the feature request!