I see it blue with black towers.
Heter det minareter på svenska?
That is correct. :)
Has gyllene no inflexion? There is no "gyllenA"?
That is correct.
How do you differentiate plural from singular (tower/s) in this sentence? I wrote "a golden tower" which was marked incorrect. Would it be en gyllene torn exclusively for singular?
Ett gyllene torn, but yes.
I am wondering about synagogue and Jewish phrases and vocabulary?
I'm all for teaching that, although it's arguably a bit outside of the scope of the course. For the next tree version, I hope to have a section on non-Christian religion that's slightly more inclusive, so that we teach e.g. synagoga and rabbi.