Language /
Endearment, friendship, etc. in Polish [38]
but the word itself isn't patronizing.
You are right. It's not. It's how it's used 99% of the time that eventually makes it patronizing. Just as "buddy" here. Or even worse, bud, pal,...
It depends on the intentions of the person using it.
Again, no argument. Here, even
fu*ck you, a-holes can be said in terms of endearment if spoken to a group of old friends and in the right voice.
In my opinion as an observer, kochana, darling, and similar are meant to neutralize the negativity of the rest of the sentence since they don't add anything of substance to it, at best, or be a putdown. Using the other person's first name will do fine.