This doesn't prevent legitimately blocked doors from being blocked, it only stops doors from being blocked by things that aren't physical objects or shouldn't otherwise block the door according to their object flag, like staircase endtiles, ceiling lights, etc.
That explains your fix, but doesn't add anything to the info you've already provided and doesn't tell me whether there is a
difference between your fix and the one at Fairy Forest, which I was hoping you would be able to elaborate on.
I did email the folks over at that site, but they haven't responded.
Yes, I know I could do some testing myself, but since your fix has been working fine for me for a number of years I guess I'll just keep using it - thanks.
(As a "Lot Builder", I strive to use mods that most people have in their game, thus my interest in finding out which of these two fixes might be better, or whether there is even a difference between them.)