Belgium is entirely left handed, despite German occupation episodes. The only exception is between Montzen and the German border on line 24. Kind of compensation for the line between Liège and Aachen being entirely left-handed. Lines built by Germans in Belgium have been built single track or left-handed. Even if the whole network is bidirectional nowadays, with same speed on both directions, there is still a concept of "normal" or "wrong" directions. Signals for wrong direction are flashing.
And you have also to take quite a détour, via Geneva, Lausanne, Modano, or even the French riviera, to avoid the French ex-AL region which is right hand running all the way from Luxembourg to Basel.
That is not correct. The former Vennbahn and its branches had right hand running until the line was singled in 1931. That's why German signalling remained in place until the end. Montzen - Aachen always had right hand running while Montzen - Tongeren was converted to left hand running between both wars.