Beginner becoming more aware of the quality of the paints I use

ArtAttack - SAA Light Red is PR101 - synthetic iron oxide. Winsor & Newton's is PR102, a natural earth - the two are very close. Going back to the question about mixing it with another colour, then, it is perhaps the 'other colour' that presented you with the problem you experienced - if you can remember what it was. On the Cobalt Blue front, it's a colour that varies quite a bit in its own right, between manufacturers, and there's also Hue versions of it, which are based usually on Pthalo Blue - that would give you some very odd mixes if you tried using it as real Cobalt Blue, because Pthalo Blue is a colder colour than Cobalt, veering usually towards green - so if you mixed it with Light Red, you'd get a dark, dirtyish green; quite useful, but not the soft grey you'd get if using real Cobalt (or Cerulean).