Wix REST API within Velo

It’s a timely question, at least for me, as I need to manipulate blog entries via the REST API. It should be extremely easy to call the REST APIs from the backend. They just require some auth information and then a simple fetch call. However, the documentation seems spotty, at least one of the required fields is not marked as such, and even the API tester throws an internal 500 error saying the split function doesn’t exist.