I’m sorry but I feel very strongly about this. This is all about your S2. Does it benefit S2 if you intentionally antagonize your X? What is the benefit?
Secondarily you are trying to nail down a parenting agreement. I don’t think antagonizing the person you are negotiating with is going to help save you time, money, and emotional energy in a legal battle.
I totally get that sometimes X may react and feel antagonized and that is his problem. I don’t think you have been intentionally needling him. People who get sucked into that vortex end up sending their lawyers’ kids to great universities.
Of course if he gets upset about something (Like the balloons) that you can’t control it’s his problem. I think you handled the last interaction great. At best from what I’ve heard in these high conflict D’s it takes at least a year if not more for the conflict to die down.
I hope you get to an agreement on parenting time soon. Hopefully that can lessen the conflict.