I took a quick look at the source code for this and it seems that it's basically a copy/paste of org-babel-execute-src-block, with modifications for asynchronous execution. I think this would make it tough to stay in sync with org because any significant/relevant changes to org-babel-execute-src-block can break this package. I think it would make sense to merge this into the mainline so that any changes to org-babel-execute-src-block don't also need to be made here. Have you considered doing this?