Hi El1,
Your first photo of the front camera. The best solution is to source a dash carpet. There a couple of suppliers on line and you can get various finishes. Once put in place you will loose 95% - 98% of the reflection your image shows. Remember darker colors do not reflect light. I bought mine via Amazon, from one of the venders and got a better deal than going direct.
Your second picture looks great, the image is what is expected, based on what I see. You wont loose the sunlight in the image/ video due to placement of the camera. I mounted mine directly on the rear glass so as to lose the carpeted luggage cover. It took a little work to run the cable through the rubber connecting pipe between the rear door and the body of the SUV, but its worth the outcome.
Your third picture is again what you would expect. Not too grainy due the amount of ambient light in the frame. With less light you will get a more grainy image. The blooming of head lights is a non-issue. With a real professional camera you would, whats called "ride the Iris" or also called "shading", to reduce and expand the light that hits the sensors. You dont have a human running the cam = That's life... A fixed lens/ Iris and sensor, is what it is. The one-board software, does try to run a algorithm to adapt the light level, and it works better in the day, in and out of tunnels etc. Than at night.
Based on photo's one, two and three I don't see the need to alter the sensitivity of either camera. You need to think about treating the dash with carpet. And maybe move the rear camera to the glass. I situated/ centered mine so the lens, is in between the horizontal elements and it stays on, even with running the rear heater elements.
I hope the feed back helps you.