Right, but the best explanation for why "Django" is spelled with a <d> is not that the <d> is silent and the <j> represents /d͡ʒ/ but rather that, as you say, the diagraph <dj> represents /d͡ʒ/.
Yes, but when somebody says "the d is silent" they're giving directions to spell and pronounce this word in English, not a lesson in French etymology. Your cure is worse than the disease.