each design includes a yellow diamond-shaped star
I have no problems with that. a quick google will give pictures of such a display (as a 4-pointed star). Perhaps you were expecting the more common 5 pointed star.
A quick look at flags will show you stars with many differing numbers of points:
3: The international brigade (or, on cars, Mercedes Benz)
4: Aruba, Nato
5: USA, Tunisia
6: Israel, Morocco
7: Australia
8: Phillipines
And there are flags with even pointier stars.
But it is just a representation. Most pictures of our nearest start show it as being almost spherical, and not pointy at all.