Well, ... twiki unpacks with perl executables in .../public_html/twiki/bin which don't run. Unpacking it into /public_html/cgi-bin/... I can run the perl, but not the html.
Attempting tricks like moving .../twiki/bin from the cgi-bin path didn't help.
At this time however, those tests were made using an owned IP; not a domain name. I may try again after the domain is moved.