Hi, Catala author here! (2) is definitely possible since the language has a formalization and is proof-oriented. I have plans to connect it to theorem provers for the kind of application you're referring to, just didn't have the time to do it yet :)
Catala is just a functional language under the hood, and its syntax is very basic (it has an LR(1) parser) with just verbose keywords.
Could you please give a short example of how we can use Catala to interpret for instance the sample program that is shown on the project page? Does it have a natural representation as a Catala data structure that can be reasoned about conveniently within Catala?