AFAIK you're supposed to install a copy of Robocode into robocode_install. But the original RoboResearch also came with a lib/robocode.jar that it used, which I only just recently realized it uses instead of the one in robocode_install/libs. I'm not sure what the problem is, but I'd install Robocode 1.7.3.x to robocode_install, start it up and recalculate the CPU constant, and copy that robocode.jar into roboresearch/lib. See if you still see a score discrepancy.
RoboResearch docs could definitely use a lot of work, but hopefully with Chase taking charge to start updating it again recently, we'll resolve some of the usability issues and keep it better maintained.