Difference between IRMS and Peak Current on Capacitor Rating
\$I_{RMS}^2*ESR=P_D\$ determines temperature rise.

Peak current is determined by destructive forces between plate foil on dielectric for a specified time duration.

Both need conservative margins for reliability.

You are responsible for correlating your design over all environental stresses and tolerances to the Do Not exceed limits of the component.  Keep in mind how Mil-Std-883 MTBF is computed and what your expectations are (specs).