Sorry, I am replying to my own post, hoping it will help anyone coming to the Maginot Line. The main warning I heard before I came was there were no bathrooms during the 2 1/2 hr tour, true. In addition, it was VERY cold. Probably was 56 degrees, but felt colder than that, with an average thickness Northface jacket on, I was pretty cold, and I don't get cold easily. Especially my toes and hands, but I wish I'd worn my sweater under the jacket and warmer socks. Also, if you are sensitive to smells, you might want to avoid this, the entire tunnel/bunker smells like gasoline. Language wise, which was my question, their web site said it would be in French only today at 14:00. When we got there the sign said tickets on sale at 14:15. Not a big deal. After getting tickets we were told the 14:30 tour was all in French and there was a 14:45 tour in German with some English. I speak very little French and very little German, but my wife speaks very good French, so we went on that tour. As advertised, there was no English, but, for various reasons my wife was not able to help much with the translations. There were some very interesting things to see but, all in all, I wouldn't do it again, mostly because of the cold and smell. To me the ideal would be to find the 2004 video from the history channel, which doesn't seem to be available right now (Amazon lists it, but unavailable).
Hope this helps someone. By the way, there are fairly nice restrooms just before you enter the bunker.
rshanes