Btw... Is there a Cirith Gurat in the lore?
Nope. There is the Eastern Guard which is meant to be a big fortress guarding the Eastern side of Mordor. It's also probably the main entry point into Mordor for the Easterlings, Haradrim and Variags of Khand.
I assume Cirith Gurat is just an official name FFG created for the Eastern Guard or is perhaps a similar castle/tower that serves a similar purpose but is more South East than East and closer to Harad than anything else.