Actually, I think that might be a bit of an odd perspective.
If the event was meant as a German event, there wouldn't be so many German speakers with English talks. For some German talks, they even provide simultaneous translated English audio tracks in the live stream portal.
So while I appreciate your 'I am just a visitor' attitude, I don't think it is fair to assume that they don't welcome English natives (think about how much courage it takes to give a talk in a foreign language). I think the event culture is more along the lines 'Most visitors understand English, so we like English talks. But since the event is in Germany, German is okay too'.
If the event was meant as a German event, there wouldn't be so many German speakers with English talks. For some German talks, they even provide simultaneous translated English audio tracks in the live stream portal.
So while I appreciate your 'I am just a visitor' attitude, I don't think it is fair to assume that they don't welcome English natives (think about how much courage it takes to give a talk in a foreign language). I think the event culture is more along the lines 'Most visitors understand English, so we like English talks. But since the event is in Germany, German is okay too'.