I will try the Alt+Tab alternative to scratchpads.
However the spatial memory concern I talked about isn't exactly of losing windows and trying to find them.
The script you mentioned seems useful to jump faster between windows you are not sure where they are. But what I tried to express is that when I'm in a workspace in i3, I have "perfect vision" of whats inside the workspace, niri I sometimes I have "tiny lapses" of having myself asking "where's the terminal, is it on the left or right of my browser?" this is not "losing the window" is just tiny frictions of having to think where a window is.
I don't know if that was a first impression that could just be solved with better attention and organization(I confess that my first try with niri was not on my work PC, but my media one that is attached to television, so I was not using niri exactly on the same mood I use i3wm).
Soon I might give niri another test drive, thanks again!