Rain X, under another name, was originally developed for the military for use on glass windscreens but was later adopted for curved non-glass canopys on the F-111. I got with the manufacturer, Raychem, and determined that the formulation and solvents should have no longterm adverse effects on aircraft plastics, but proving that fact was not something the USAF wanted to pay for and it was not restocked.
Renamed "Rain X", it was soon released in the same plastic bottle (color changed from blue to yellow) for public sale. To the best of my knowledge, nothing changed in formulation or manufacturing. It is still a better product for glass than plastic materials because it bonds better to glass, but it works on both. I don't know the plastic used for the Leaf back-up camera lens, but anecdotal aircraft data says there are no longterm effects on either polycarbonate (Lexan) or acrylic materials. I use it occasionally on our car windows (Rain is not too common here in the desert!), but have never used it on the camera lens. Dirt is more of a problem on the back of the car and regular washing seems to keep it clean enough.