The base plate doesn't really click in. But it fits perfectly and stays in place. Like it was designed for this!
Another question for you: Those train signals in your picture, are they purely decorative or are they connected in a way to the switch
I'll have to take a look at my baseplates and play with them a bit to see what they can do. The signals shown in the pictures are for looks only. They are from Playmobil. I do, however, use LGB #5092 signals to control my switches. They connect to the LGB switch motors. I'm not sure if you're familiar with these, but they work really well.