No, Scotchtint window films do not cause seal failure. We've been applying Scotchtint films to insulated windows for over 15 years with several millions of square feet of film applied to date. Some of this heat will transmit to the airspace, slightly raising the airspace temperature. Risk of seal failure is greatly determined by the quality of workmanship and the quality of the materials that go into building the insulated glass units. The best guard against seal failure is to purchase well-made units from reputable window manufacturers that have solid experience and histories with insulated units.
Nothing stops fading.
However, if the typical life is only 2-3 weeks, then the expectation should be expressed in terms of months. It does not loose its effectiveness over time.