I'm really sorry for the complexity. Complexity comes from my lack of experience as a coder. But I had hoped that my comments and the structure will make it easy to modify.
The only script you should need to edit is puzzle_inc. It has a section called CONFIGURABLE with some constants you can tweak as needed. You should be able to find the functions in that script that you can customize too. There's a function that executes when its all completed. One that handles the display of the count and so forth.
As far as handling blueprints goes I set up the switching placeables (the one the player needs to use) as all having the same tag. This allows you to simply place them in the module and the script will be able to generate a count of how many toggles need to be toggled (I had initially stored them as a list but that seemed needless).
As you can also see, there is a master placeable that needs a different tag and a unique one. There should only be one of these. At present it is the thing speaking the count, but you can set that to the player if you want. This master placeable is key to the whole operation as all the code executes on it, and it stores the state of the puzzle.
There is also a placeable that can be used to reset the whole puzzle. I did this for testing purposes because the way I set this up, if the count reaches 0, then the whole thing gets stuck in a fail state, and the player can't interact any further with the switches. To start over you need to reset.
Also when the puzzle is successfully completed, the puzzle resets to start.
You can see all this behavior by playing with the demo.
If you have any questions, fire away. I'll answer as best I can.