Important statements here:

The cable gland shall be selected to match the cable diameter. The use of sealing tape, heat shrink tube or other materials is not permitted to make the cable fit to the cable gland.

Cable glands and/or cables shall be selected to reduce the effects of "coldflow characteristics" of the cable.

NOTE 1 Cables employ materials which could exhibit "coldflow" characteristics. Coldflow in cables can be described as the movement of the cable sheath under the compressive forces created by the displacement of seals in cable glands where the compressive force applied by the seal is greater than the resistance of the cable sheath to deformation. Coldflow could give rise to a reduction in the insulation resistance of the cable. Low smoke and/or fire resistant cables usually exhibit significant cold flow characteristics.

Coldflow?

First ever I met Ex conditions I was told to fix the gland as tight as possible. Only problem might be here the outer cable shield... it might react on phisical strength and flow away towards both sides - this is coldflow... very annoying... no IP, not fix at all. Only problem it comes few minutes later as follow up installation. Both installateur, but Ex inspector may be asked for their responsibility in case of non-compliance.

Cable manufacturers shall make their statements upon, they really shall... nobody does! Again, they shall... pls check it!

Keep up good work!