Hello,
Why when we buy a gyropter through the "Guishop" plugin it appears in front of us but when we buy it through the "ServerRewards" plugin it appears above us and crushes us?
I specify that both use the same command "
spawnhc Mini $ player.x $ player.y $ player.z save ""

That is because GUIShop has special logic to handle spawning vehicles and such so that it does not kill you. 
Not sure why you posted this issue on GUIShop since it sounds like this is a server rewards-specific problem.