Bayeux to Frankfurt

The shortest route option is 7:23. Travel day indeed.

You could train into Paris and fly to Frankfurt. That would cut 2.5 hours.

Another option would be by car. It does not save much time but since the train is not saving you any time, it could be worth a price savings. Just drop the car as close to the boarder as you can and train the rest of the way.

It would probably take just as much time to fly from Paris to Frankfurt by the time you travel to the airport, check in and go through security. Might as well take the train the entire way. We spent a week in Normandy and needed a car. We took a train to Paris from Germany and then got the car. Not for the faint of heart to get out of Gare du Nord in Paris, but it can be done.

I speak some German but no French. How difficult are French train stations to understand? Will it be hard to make connections?

Not difficult at all to find your way. And if you are pre-purchasing your tickets, they will have it clearly marked the platform and car as well as seats. However, it looks like for this journey you will have to change stations (from St. Lazare to Est or Nord). So that will be a bit of a challenge as you will have to cart all of your stuff through the metro (RER E runs between St. Lazare and Nord but it is a bit of a hike to the RER station from the train plaform and if you are leaving from Est you will have a bit of a walk from Nord)
...or probably easier to get a taxi...which shouldn't be too much of a headache.

But the train stations themselves are pretty straight forward to navigate for an English speaker.

The easiest but longest option would only have one transfer--from St Lazare to Est and gives you 2 hours to make it around lunch time...which will be a good stretch and chance to eat.

The next best option only gives you an hour in Paris, but you leave from Nord so the transfer is easier. You would also have a transfer in Cologne (Koln) but that would be an easy transfer (noting that you would still have all your stuff).

Thank you for all your great suggestions! Is it less expensive to buy the train tickets now rather than wait till we get there?

Purchase them as early as you can for best pricing. You can book about 90 days out.

I use the voyages.sncf app and get better pricing than raileurope. If you don't speak French, tell the app your are in Belgium or Netherlands to get English. Then tickets are stored within the app which makes it easier as well.