Hey John, those holes are probably cut for the molded plastic servo mounts made by Multiplex and Graupner, among others, commonly used in scale and f3B/E sailplane wings.

It's much simpler/faster to use a large Forstner bit to cut clean servo holes rather than routing square holes (been there done that). You can make quick fillers for the holes by using the appropriate sized hole cutting saw and 3-4mm balsa sheet.

I've been eying this kit for a while as I am considering an MW44 sometime in the future...thanks for the thread.

Barry