This is a pretty common problem with any solid, one way wall. The penetration model is based on the surface the bullet enters, which in the case of this one way wall, will be brick on one side, and glass on the other. Bullets will penetrate glass or cardboard far better than brick, concrete, or solid metal.
using sv_showimpact_penetration, you can see that just on that wall, a shot from an awp will lose 83 damage (of its 115 base) penetrating through the brick and out of the glass. The other way, it will lose only 21 damage. Add in the 40 unit long double-sided glass, which drops the damage by roughly another 26, and you have an awp shot that penetrates one way for 6, and another way for 68.
This doesn't change the fact, that even if the damage were the same, its still a one way so one team is going to be at an inherent disadvantage.
Just make it so you can't utilize a one way wall during a warday as a guard ?\_(ツ)_/?