Using build 1.6.4-4.0.5.12 - states on site that this is built against multipart xxxxx.191, that is installed. On serverlaunch, projectred crashes stating that it could not find version xxxxx.182 in /server/mods/1.6.4/

It seems to me like PR is using ONLY the specified version. It should except higher versions as well, since most of the time, they will work without a problem.