Unequal pressure on the cross section of the film, while in roll form, and possibly due to the difference in dimensional stability of the emulsion compared to the film, caused the film to curl in the first place. So pressure and/or heat could be used, over time, to reduce the stress in the film and possibly the stress between the film and the emulsion, but the emulsion can develop cracks when stretched. Keep in mind that after "flattening" the film arbitrary changes in pressure and/or exposure to changes in temperature could start the curling again, as different substances react differently dimensionally to changes in temperature. Keep in mind that of the two materials, the emulsion is the most delicate, before attempting to apply any stress to the materials.
With that said, contacting your film supplier for their recommendations would be a good first step.