The headgear "H_Shemag_khk" and "H_Shemag_tan" both have the same hiddenSelectionsTextures, which is the texture for a helmet, not a shemag. As a result, the texture of the shemag is incorrect. This can be seen both in-game and on the Arma 3 assets page of the wiki.
I think this is the line that is incorrect in their configs:
hiddenSelectionsTextures[] = {"\A3\Characters_F\BLUFOR\Data\equip1_co.paa"};