Learning about making jams/jellies and trying to understand how to properly substitute ingredients in a recipe

I am interesting in making a peach hot pepper jam and I came across this recipe by surejell:

https://www.kraftheinz.com/surejell/recipes/579451-peach-hot-pepper-jam

I also found a "regular" peach jam recipe on their wiste:

https://www.kraftheinz.com/surejell/recipes/501298-sure-jell-peach-jam

The hot pepper version replaces half the peaches with peppers but uses 1 cup of vinegar instead of the "regular" peach recipe that uses 2 tbsp of lemon juice and a produce protector. Would using the 1 cup of vinegar make the jam more "watery" ? I am wondering if I can just start with the "regular" peach recipe and replace half of the peaches with peppers?

I've also noticed that some blueberry jam recipes don't include leon juice or vinegar. Is this because blueberry is already very acidic?