Lasers have been evaluated as to whether they will interfere with fillers, and it is safe to say that they will not. IPL is like a super-powered flashlight and is not a laser, but since it is a weaker version of lasers with regards to cosmetic outcomes, I feel safe extrapolating the laser data to expect that IPLs are safe with fillers. As for penetration, there are definitely some wavelengths that can penetrate deeply. For instance, red and infrared weavelengths can penetrate 2-3mm into the skin and this is where fillers reside, but there are no components of these fillers that I would expect to absorb the light thus impacting their location or effect.
After reviewing the data on procedures for cellulite for the book chapters on the subject I have written, it is safe to say that nothing works. Cellulite is present in >95% of the population is a result of normal anatomic architecture.