Neighbor's swale is flooding my yard

I have a home in Ohio that sits in the middle of a long sloping hill. My neighbor on the high side has a swale that drains in to the middle of my backyard at the property line. My yard only has a slight grade so some of the water runs across to my lower neighbor, but much of the water runs up toward my house, across my patio and then down the side of my house. I am trying to catch the water nearest the swale so that it does not have a chance to move across my yard. My plan is to use a catch basin and 4 inch PVC pipe that I would tie into my existing downspout line. I also want to put french drain along the patio and the high side of my house to help take the load off my sump pump that only gets water from the back of the house. The french drains would also tie into the same downspout tile. This downspout tile already has 2 downspouts connected to it and is 4 inch in diameter. It runs down my sloping front yard to the street. The front yard slopes at nearly at 45 degree angle. I am wondering if this is too much water to place in one 4 inch tile? As a back up, I am adding a pop up about half way down the front slope to act as a pressure relief. Will this be enough with the heavy rains that we get in the midwest? I am afraid that the water could back up in the downspouts and overflow the gutters creating too much water at the foundation of the house when we get heavy and fast rains. Appreciate any advice you can give.

First and foremost, I'd contact the neighbor and have them fix or move the swale so it's legal again. Most everywhere says you can't dump nor cause water to flow onto neighbor properties and especially toward or directly at any structure. You can offer some payment assistance or you can use the same re-grading contractor to work together (all 3 of you) and handle the water entirely with intersecting swales. Or thereafter, complain to the Municipality and have them force the neighbor to correct the situation.

- I'd only go with the above, as I don't feel your downspout line will be at all sufficient. I would expect any surface water of that amount would need TWO 4" lines from the catch basin. And, why install something that needs constant cleaning and flushing, when there's apparently plenty of slope (not much at all is needed) and yard everywhere to keep everyone endlessly happy and dry...I do this with an 8-inch wide by 8-inch deep ditch (ankle twister swale) and it still spills-over a couple of times a year.