I checked this. Existing mc_projects_get_user_accessible works. It takes longer (3.7 sec instead 1.1 sec) and results in a longer response message (886340/38249 instead of 227527/14095, plain/gzip) but this is ok for me. Probably it was only a problem at the time nusoap was used. I use the default which is SOAP now.
I will remove this function from this pull request.