Finally caved and made an account here after being a long-time lurker...I am also a semi-finalist for research in Germany and am in the same situation where all my research would be at an English-speaking institution. I am a beginner in learning German too, but I have been trying to do Duolingo lessons lately.
Just to follow up on the other responses I'd like to add that Germany has not done interviews in the past, and I don't think they did them this year either (at least I didn't have one). The language requirement is different for research vs. ETA. For research, it says that they recommend 1 year of study (or novice level), whereas for ETA they require 2 years (intermediate level). You can find those details under the award descriptions here: https://us.fulbrightonline.org/countries/selectedcountry/germany
I'm not sure how much they care about German speaking ability for research semi-finalists. Hopefully not too much!