At this point I look at enemy spawns as they are either drag ins or directly spawned. You sound like you are wanting direct spawns. Then I ask myself “Where to spawn?” and “When to spawn?”.
Work out when you want them to spawn, and then use a “Spawn actor of class” node. It seems and maybe I am wrong here, most character and enemy / npc spawns are done in the game mode. That node will let you set where to spawn them in X, Y, Z. Figure out the correct elevation in your map (Z) that way they are at least level with the floor. Then you just need X and Y. You could try randomizing the location a bit (within 1 to 5 percent for example) or the times you would normally spawn them.