How to soften the recessed lights without replacing them?
Consider that any film you put across the opening of the can will hold heat in. Heat is the enemy of the electronics in the driver for your LED bulbs. Well, heat is the enemy of all electronics. It will also hasten the death of other types of lighting, and could, potentially, trap enough heat to start a fire.
I would consider a dimmer, allowing you to adjust the brightness to the situation - sometimes you'll really appreciate 3600 lumens in your living room, other times you'll want a tiny fraction of that.
I'd also consider a different color temperature bulb (if you have replaceable bulbs). You say that the lights are &quot;bright white&quot; which means they're in the 4500-6500K temperature range. A 2500K bulb will be a much yellower light (more light incandescent) and won't be quite so harsh on your eyes. However, it will seem to be dimmer, even at the same 900 lumens, when doing any sort of detailed work. Somewhere in the 3-4000K would probably be sufficiently bright, while still being easier on the eyes.
The ideal would be a bulb that is both dimmable and can change color temperature. Usually, these are controlled by a phone app and/or a home automation system.