I understand - fully - the value of softening a portrait - at least, most of them.
I've struggled with "softening" filters and various devices, and the most effective application has been the addition of softening filters on the enlarger lens. Capture with all the resolution (etc.) that you normally would get, - it is FAR easier to reduce that in printing than attempting to increase resolution after exposure.
This discovery came as a result of finding two 40.5mm softening filters - brand unknown - but who really cares - in a "used" box at a large photo supplier (with eBay, gone now - another story) - the size fitting my Rodenstock enlarging lenses.
One for mild softening - two, piggybacked, more intense.