Is it considered cheating/glitching to climb into the roofs in Brest?
I discovered that over by the room where the dynamite crate is, you can climb into the roof if you turn to the side and move to the perfect spot. From there you can access a number of roofs and the walkway above the large gate.
No. There are certain buildings where the roof is just low enough that you can climb up onto it. Actually just watched your Youtube video doing Brest covertly and you climbed onto the roof at the exact spot I'm talking about, so I think I found my answer.