Programmatic (not procedural) Level Creation

You don’t really need a plugin for that if you don’t want to make one.
You can do it through one actor’s construction blueprint graph. Every time you create/place an actor or change any of it’s params, the construction graph is executed.
Your external data, you can import as CSV data, just need to create an importer struct in C++ for it then you can use anyway you’d need them.