I don't use Typst myself and am not familiar with Cetz. From the docs it looks like it's in early stages of development, so it doesn't feel like the right time to do this to me (or at least should be a separate, perhaps forked, app). But certainly it would make sense to develop bidirectional converters that could in particular be used at file open and file save in this app.
A converter would be fantastic, too. I experimented with having a few LLMs try to translate TikZ to Cetz and none of them were great.
The best thing I have found so far is tylax (https://github.com/scipenai/tylax), which I think is a parser with rules, not a statistical model.