While you cannot access the Level blueprint from any other blueprints, you can access GameMode, GameInstance, and GameStates blueprints from pretty much any other blueprint including from Level blueprint itself. What this means is that instead of saving your Waypoints array in the Level blueprint, you should store them in any of the other mentioned blueprints (i.e. GameMode, GameInstance, or GameState). If your game is not going to be multiplayer, then it might not really matter in which of these blueprints you store this array. Let’s see how it can be done with GameMode:
Create a blueprint based on GameModeBase (Let’s name it BP_MyGameModeBase). Open it and create an array variable of your waypoints type. Compile and close it.
Go to your Level blueprint and store the waypoints’ array to your GameMode as such:
Remember that you don’t need to store these in Level blueprint anymore.
Now in your AI blueprints, whenever you need a reference to these waypoints, simply get the game mode, cast it to your BP_MyGameMode, and then get the waypoint array stored inside the GameMode.