Why don't Orcrist / Goblin-cleaver and Glamdring / Foe-hammer glow like Sting when orcs/goblins are near?
In the book, they did.
Chapter 4, Over Hill and Under Hill, page 64:
(Gandalf wielding Glamdring the Foe-Hammer/Biter)
Why they don't in the movie, is never said. I can think of no in-universe answer.