It used to be that you couldn't just plug in Cycle.js to JSX by default, because the function used for virtual-dom node creation had a signature that slightly differed from what JSX expects. These days @cycle/dom exports hJSX [0], which is compatible.
[0]: https://github.com/cyclejs/cycle-dom/blob/master/docs/api.md...
(I would have sent this by email, but you haven't put an email in your profile. It needs to go in the about: field, not the email field. )