Geneva Convention does NOT specify or restrict sighting equipment. Those sections dealing with infantry weapoms deal exclusively with restrictions pertaining to projectiles. There is no mention of "snipers" or any other special classification, the agreed restrictions are general rather than specific.
For what its worth: The original Geneva Conventions were isnstigated by the Wermacht at the turn of the 20th century. The British arsenal at Dum-Dum in India had developed a superior infantry projectile that expanded. The Kaiser's army was worried that this would give the British Army a big advantage in the upcoming brouhaha, so they manuevered the French, among others, to lobby for an international convention to outlaw these "inhumane" projectiles. The convention was held in Geneva.
Other things outlawed in various Geneva conventions (that were promptly ignored) have included all sort of flame throwers, poison gas, explosive projectiles under 13mm, and lots of others.
Many countries (including Japan) never signed the Geneva Conventions, but the winners decided to apply their rules to the losers.
Back to the original question --with a 4X restriction, I would go with the German #4 reticle-- with choices presented, though, I would go with the MP9. I find that the Russian sniping reticle is probably great for what it was designed for, but for paper punching or hunting, it would have a long, steep learning curve. Some people enjoy suffering, though.
I have scopes equipped with these reticles mounted on various rifles, and while I cannot comment on the worth of various sniper reticles, never having the training, or experience, I have shot a fair amount of paper at some ranges going out to silly, and have cleanly killed big game animals out to my personal limit of confidence ( well under 400 yd under most conditions).
