You are quite right the semi-circular rule even Westbound/odd Eastbound applies in the RVSM airspace over France.
That said,the system considers not the segments of an airway, but the whole length, thus avoiding numerous level changes when the orientation of the route oscillates either side of the north/south compass.
For safety reasons,when two airways passing over a common waypoint diverge from each other,the system will keep them in the same odd/even level table.
This is the case for awys UM731, UZ131, UN855, UN869, UQ169, the headings being respectively 147°, 163°, 181° 236°, 240° ,all originating from OLRAK ( this waypoint is 20 Nm NW
of Mende.The reason is the importance of the traffic from Paris on the UN855 which forces the westbound UN869 to adopt the odd list.( Airway UN869 comes all the way from Germany)
Hope it helps.
And anyway if you came to see me, I would give you a tutorial on air nav maps and approach plates.Free !
looking forward to hearing from you soon,