If you're going to buy Sriracha sauce, look for Shark brand - it has none of the additives you mention, and it's frequently highly recommended by Thai cooks ( Sriracha sauce
). Also, the brand you've mentioned is made in USA (not that in and of iteself is a negative, but it's not quite as authentic as some Thai brands), and is known to have been counterfeited. I'd be cautious with that particular brand. That's not to suggest not using it, but just be careful. Here's a web page that describes what to look for in counterfeit versions: Counterfeit Sriracha Sauce
The article is a few years old, and I don't know if the counterfeiters have been stopped, but this link at least tells you what to look for in the real product.
I've tried to get some recipes for making my own, but have not had any luck so far.