you should be able to redirect stdout right? Nextjournal works great with rcf OOTB : https://nextjournal.com/dustingetz/missionary-relieve-backpressure

failing that, there are reporter extension points - see source code

in my clerk notebook, the code from that example, doesn't return the test results to the rendered page, it returns nil (see picture) ill try to look at the source code for inspiration.

it's displaying the expression result nil without the prints

Are they going to your terminal? The prints must be going somewhere

there going to the cider-repl buffer.