I think I may have cracked this. When playing a title in Disney Plus through DRM Downloader, I noticed a little icon in the top right corner of the screen I don't normally see when I watch Disney+ via the TV app. I clicked on it and it was a language menu with Deutshe as the first option, and selected. I selected English and everything switched over and it seems to remember it between visits.
steamheaduk
I had the same issue, but my Disney+ settings had the audio track set to English [UK], and it was still downloading German audio. I switched to English [US] which fixed the issue. If the above-quoted recommendation doesn't work, I'd try selecting the next language listed to see if it is reading the audio for the language that is above the one selected (in the app). That may also be a temporary fix.