During the french strike the engine test bay was notified as unavailable because it was to be avilable for parking, if it was used I do not know.
Also taxiways Q and P double as stands and taxiway, but that also means that if you lose them as taxiways there is even less flexibility and less space to put moving aircraft, or aircraft waiting for blocked stands.
In terms of space there is very little slack, it's not uncommon for aircraft to land even in the middle of the night and have to wait for a stand. Also common to see widebodies parked remote due to lack of stands, and stands like 100, 101 and 66R are commonly used for routine parking as well due to lack of space at the terminals.
From what I've heard the stands will be reverting back to aircraft parking when the new car park under the 23R approach is finished. If that holds true though I don't know. The bit past stand 216 has even been taken out of the AIP parking chart.