It sorta depends on the ingredients you’re working with, some tomatoes are sweeter or more acidic than others. Where I live tomatoes tend to be somewhat watery and lack a bit of intensity of flavour. If I’m making sauce at home I’ll taste a bit and add some sugar and/or red wine vinegar to balance out the flavour.
Meh. There’s plenty of room in the gray zone between “car” and “motorcycle” where things like this or this can exist. The botanical world has worked very hard to create rigorous definitions of fruits and vegetables only to be completely ignored by cooks. The culinary world in general has done just fine for centuries without rigorously specifying whether taco’s are sandwiches and cereal is a soup.
As long as it is generally understood what people mean by a word when they use it everything will be mostly fine. REST is an understood term, whether the inventor of the term meant something else by it is immaterial.