The safety issue is the pH. If both recipes have adequate acidity, then I cannot see how combining them would make them less safe. If in doubt, use the vinegar ratio in the recipe that has the most vinegar. (not a food safety pro)

Joanne, If I wanted to decrease the spicy result, I would probably omit part of the hot peppers in the zesty recipe. You can swap out an equal measured amount of chopped bell pepper for the hot pepper....i.e. use 6 cups of bell pepper and 1 1/2 cups hot chile instead of the 5 cups - 2 1/2 cups ratio, or, omit the tsp hot chili sauce in the zesty recipe too.

When in doubt, I frequently increase the amount of vinegar in a canning recipe.

Maybe this is a stupid question, but why can’t we just add citric acid to salsa, just like with canned tomatoes?

Not addressing the canning question, I once added just a touch of citric acid to a small batch of salsa -- thinking it would "brighten" the flavors. It didn't. It made the salsa taste like citric acid. Tread carefully. lol!