Spraying doesn't really do anything important in low/slow cooks. Mopping (with something fat-based) can add a bit of an evaporation barrier but this is not really necessary, certainly not for cooks where you're going to foil. Spraying (not fat-based) can cool the meat surface on significantly higher temp cooks but that's not what you're doing here. It will not tenderize, add any significant flavor (unless you're using something concentrated and then it's relatively minimal), or improve cooking. The problem you had is cooking by time, i.e., cooking X amount of minutes unwrapped and Y amount of minutes wrapped. . When I used to post this board all the time years ago it was my constant refrain (that and responding to bacterial/food safety issues and repeatedly reminding everyone that sell-by dates are utterly immaterial).
Once you wrap your ribs you need to check them for "done". Time does not determine done (and internal temp doesn't either, btw), only feeling the meat will tell you if you've hit it yet. This goes for unwrapped meats as well. If foiling you can either stick a probe right into the foil (in the case of ribs, in between bones; brisket or boneless butt, halfway between the thickest and thinnest parts; bone-in butt, thickest) and feel how the probe goes in, or you can unwrap first. When tender it will go in nearly effortlessly. Some resistance, almost done; more resistance, more time needed.
