I have no issue with lots of non-English speaking folks aboard, but frankly, I think it'd be very difficult for me to go on a German speaking cruise where the lectures (which you said you wanted) would be in German. My German isn't good, but maybe yours is? I was looking at Ponant and had no fear because my French is good enough to get through the lectures.
Have you tried to find YouTube videos from people who went on the cruises you want? I saw where one Ponant cruise made you wash your own boots with a brush and I was not impressed (or maybe I was extremely impressed, in a negative way). So I would have to confirm that it's a newer ship with the boot washing machine. Apparently, I'm the only one concerned about that and the smells. But I learned from YouTube that my ideal time is November...pristine snow. 🙂 March is whale season, but you wanted Penguins and apparently, they are out in Nov, however, it's pre-chick season. I learned that the high season is Dec/Jan.
I noticed that the bargains (like no single supplement) are Nov and March. I heard that March is too late for penguins and more about whales. I want penguins and I want to minimize the poop mud. I also don't want to pay the airfare at holiday seasons (Christmas/New Years).
From my observation, you might consider Hurtigruten since they offer no single supplement for the less popular voyages. The one I want is on a ship with no balcony...which is not ideal so I am going to keep shopping. Also consider 2 days in the Falklands and 2 days in South Georgia. If you watch the videos, you can decide for yourself if you care about those areas or just want to do the peninsula and some other areas in South America.