Feynman diagram and uncertainty

There are no axes in Feynman diagrams. The only important part of a diagram is what is connected to what, and not the relative orientation. You can move around the pieces of a diagram and, as long as you don't break any line, the value of the diagram remains unchanged.

You have to realize that the Feynman diagram is a schematic representation of the integrals of the scattering amplitude , necessary to calculate the integral for that order. All variables will be integrated within the limits of the integral, so it is not a real space and time but an iconic one seen in a Feynman diagram. The result is a crossection, or a lifetime for that interaction, or an angular distribution. Quantum mechanical probabilities are all there.