I will have to see if I can try.
I wonder if this is the same issue as with Peacock (here) if downloading 2 audio streams you only get Spanish.
The only answer for that on Peacock is to download and select only English, name it moviename[English], and then download and select only Spanish and name it moviename[Spanish].
As sadly I don't see this getting fixed very quickly along with their time off now until at least Feb 4th.
ADDED: Ok, no, not the same issue. You only get Spanish as a selection, you will have to go to SF settings and change the settings for Netflix from EAC3 to AAC. You will then get English as an option.
Netflix at its best :/