Paris Nord Train Station

I don't recall anything particularly notable, but, you can find videos on youtube
that walk you through various aspects of getting through just about any major
train station, and they are often quite current.

Similarly, I don't recall the platform area being confusing. As I recall, very well marked. The station is large, but you will need only a small area.

There are online maps. The above Youtube suggestion is also good.

http://www.gare-du-nord.paris/plan-gare-du-nord.php

The only thing I suggest is that you make yourselves pickpocket proof by having your valuables in a money belt worn under your clothing. There are the "petition girls" who sometimes roam thru the station and they are just a distraction for picking pockets.

There are some decent food kiosks as well so pretty easy to pick up a sandwich/chips/drink for lunch on the train.

The trains are all displayed on the reader boards overhead so keep an eye on the number of your train to Aachen (and know the end destination of that train if Aachen is a stop along the way.).

Thank you! I will check out You Tube for sure. And, thanks for the pickpocket advice as well.

If it is the Eurostar, then the trains final destination will be Cologne.