Good to hear you got the basics working. So the main reason this is isn’t working is that you cannot reference a specific static mesh like this. You will want to use an actor with a static mesh attached instead.
Another suggestion is to not include important events using the action system. My action system should only be used for displaying stuff to the player. The reason for this is that the server side code happens instantly while the action system is a queue where the action happens at an unpredictable point depending on whatever actions are queued up beforehand. This means for instance that if the AI on its turn first moves, then spawns a mesh and then tries to interact with the mesh it will not be able to, since movement happens instantly server side and the mesh is not spawned until after the slow movement animation is done. Check out my three tutorial videos on the action system for a more in depth explanation with examples.
So how to do this in your example? You need to disentangle what the server sees and what the player sees,since these might happen at different times. To keep this close to your original solution you could spawn an invisible actor server side and add the reference and then make it visible as a queued action. This will look just like spawning to the player, but give the server earlier access to the reference.
Hope that clears things up and solves your problem.