it’s quite interesting that nobody has reported the issue I had with my front camera module so far: My new front camera module was not taking pictures that were too dark (as often reported in this thread), but instead my front camera pictures were much too bright.
So i then found this post #155 within this thread, that lead me to the settings of the pre installed default camera app, where I could adjust the settings of the front camera from 1.9 MP to 5 MP. And hurra, the front camera was taking pictures that just look perfectly fine now!
However, what makes me wondering, is the fact that I had installed the latest update 18.01.1 which should actually fix this problem. But obviously, this has not worked for me, so the fix did not set the front camera resolution from 1.9MP to 5MP.
Hope this helps others too