If the plugins you find don't quite do what you want them to do, you should be able to make it work using the event system. I read about Functions in Construct 2 today and that they could be used recursively (which means that the Function can call itself) and thought that your particular problem would be a good exercise to work with it.
Here is a capx that matches adjacent tiles of the same colour. Any tile to the left, right, top, or bottom is considered adjacent. I think this is the behaviour you're looking for, although this is not necessarily the best way to implement it. I was just having some fun, and wanted to show you that what you want to do is possible.
Left click to match, Right click to change colours. Enjoy!