Hey, you are pretty much right.
If you currently have your run on server event on the shooterhud that won’t work because the shooterhud only exists on the client. In addition to that for a successful run on server you need to call it on a replicated actor that is owned by the player, such as the playercontroller, pawn, weapon or buff.
It really depends on your mod and stackability requirements. If you work on a total conversion there is no problem with placing the event on the playercontroller, for mods your mod will need to be first in the load order to work if you modify the playercontroller or pawn. Weapons and Buffs are stackable but not always applicable.
If you want to dig more into the replication in ue4 i recommend reading this: http://cedric.bnslv.de/unreal-engine-4-network-compendium-released/