I think you can try setting the LanguageTargets property. See here how the SDK determines the language based on file extension: github.com/dotnet/sdk/blob/2…
I have not tried this myself, I just ran across it while looking for something else. There may be more properties.
#LanguageTargets are crucial not only in a #DualLanguage classroom, but in every classroom!! Without them, ss are not being held to expectations to use the language and the #literacy skills we are fostering get lost! Especially in DL, where lg dev is the ❤️ of our instruction.