Depending on the budget for this window there are several options. Have a new window installed designed of real a leaded glass or solid pains of a tempered textured or frosted glass. Another, less expensive solution, is to have a frosted treatment applied to the existing window panes. There are window clings that offer stained or leaded glass look but are limited in the size that are manufactured. Hope this gives you some ideas.

Thanks, Clarice! Curious if you’ve ever seen leaded glass in a window like this? I’d love to find some examples, but haven't been able.

Bet that would be a $$$ window to replace. There is a window film simulator on the 3M site that might help. (But even for film, you'd need professional help or an expensive ladder to install!)

https://www.3m.com/3M/en_US/home-window-solutions-us/window-film-simulator/

Good luck!

A distant view through a second-floor window of a staircase/hallway is not really a problem for most homeowners. I'm assuming the house doesn't have all the lights blazing through the night.

Consider the new passage lights that are incorporated into the wall outlets to keep the overhead lights off. Then the view will simply be dark.

We actually have these!

https://www.wallpaperforwindows.com/product-category/leaded-glass-film/