@Apey
We have some similar Japanese Maples in my town. I visited them yesterday and I looked on the ground hoping to find some helicopter seeds. It turns out that they remain attached to the tree and they are very small. I removed 50 or so.
I will dampen some vermiculite and cover the planted seeds with cellophane and store them in my refrigerator over the winter. I will put them out next spring and they should sprout.