libsndfile.tcz is a dependency that provides libsndfile.so.1, and since using a wrapper to specify /usr/local/lib as a path sounds like ldconfig has not been run since the installing of libsndfile. Of course that should happen automatically with installing the extension.
Audacity works here when installed from the appbrowser.
This is a legacy version, packaged in it's own directory to leave room for the current audacity without conflicting. Perhaps someone will create a current audacity.