AFAIK in league you can’t add any units to China or to France with a bid, and you can only add units to territories or Sea Zones that already have units.
The Chinese bid is perfectly legal in the Global `40 league (unless it just changed). Strictly speaking it is also legal to bid Chinese units which they cannot buy in the normal course of a game, but that probably will be changed if it hasn’t already. There has been plenty of discussion on that topic.
Placing a French bid in Paris should also be perfectly legal. I don’t think doing so would be that helpful since at best maybe you’ve delayed the German attack on S. France or Normandy by one turn, which i don’t see as having a lot of strategic impact on German play.
Not sure 4 extra inf will most likely trade for 2-3 german tanks. And will leave normandy and south france alone. And no G1 attack on russia. True the effect in china might be bigger but it will make the attack on france pretty dicy. Just a bit of bad luck and you might get it back with france on its turn 1, of even keep it.
It is not only what units do but also what they make your opponent do.