As stfrn says the team (and the mainteiners, since they are in the team right now) uses the \"official\" code, which is based on the freeze date decided for specific circumstances (usually, some particular change in CS code).
This is quite clear in the IRC channel #planeshift-build where even the topic shows which is the date of the code.
Using a newer version of CS/CEL and even Cal3D can causes problems or different behaviours, which may be hard to track down.
When the PS team will decide to change date of CS & co, we usually change the topic on #planeshift-build, or anyway we give hints about it (as stfrn says in history.txt or in the thread \"weekly update\" in this forum branch).