Thanks!
I think the directory permissions might be at fault (depending on what user/group is the Urw binary executed as.. not sure about how Mac handles that). In short, permissions "r-x" in second position, for a directory, only allow reading and modifying files, not creating them.
So if the URW program is executed with a user NOT belonging to the group "staff", it would only be able to modify existing files but not create new ones.
I don't know if the above is the actual reason - it would be nice to test it. If you want to give it a try, just move the files urw_ini.txt and urw_ini_tmp.txt outside the directory, then type:
sudo chmod 775 urw3-Darwin
on that directory. This should change the permission line, when using "ls -ld", to:
TARDIS-AIR:urw3-Darwin bethefawn$ ls -ld
drwxrwxr-x 105 bethefawn staff - ...
Now just open URW again (it should be closed when doing the above) and see if the settings get persisted