Actually, Indians have been using red chilli powder in their recipes for a long time. Paprika isn’t a traditionally Indian spice so I will refrain from commenting on that.
I absolutely do not support cultural appropriation in any form. I believe, however, that it’s okay to modify a traditional recipe to suit your own palate. The English version of biryani is nothing like the Indian varieties of biryani — similarly, the Indian version of pasta alfredo is nothing like the original alfredo. But everyone’s enjoying their own twists on dishes, so as long as you are not trying to market your version of the dish as the authentic one, I think it’s okay.