It is very hard to make proceduraly generated maps using blueprints.
And that is for one reason, construction script is very limited, and doing all logic on Begin Play (in runtime side of script) prevents you from seeing map in editor, also makes everything movable.
I did some dirty tricks that force construction script to do more than it should, but that makes whole project unstable.
You have 2 alternatives:
- code everything in C++ yourself
or - buy dungeon architect, that is very good plugin, actively developed, and its best you can get without coding it all yourself in C++