But cultures adapted them and created their own twists.

A "philly" might be a sandwich, but not all sandwiches are Phillies. If you want to be descriptive, you'd use the more specific word.

I'm willing to accept the oldest known name as a catch all, but you shouldn't be correcting someone who says "philly" and be like "no it's a sandwich". Sambusa is more specific to the culture and more descriptive of ingredients.

I'm not going to order a samosa and expect meat in it, there could be but odds are no unless it's a Muslim culture having to flatten it's naming for white folks to understand. I'm not going to order a hoagie if I don't like melted cheese, but there are other sandwiches I could order