Do you understand what the phrase "Spatial Finder" means?

You say: "windows open in exactly the position of my last window" (hint: this is called browser behavior, not spatial behavior)

Spatial Finder: windows ignore your last window and open to "whatever I sized it 3 weeks ago" (each window space, position, size, etc is individually remembered by folder)

You would be served to read up some Finder history, like the link to arstechnica featured on the github, so you can understand what Spatial Finder means before weighing in on a tool specifically designed to bring back that feature.