Hi Finn
There is quite an array of solutions for decoding.
You will have to consider switch bounce. I did some experiments along these lines using a simple Arduino sketch which you would have to adapt to RPi (Python ???)
Results here
Encoder Module with button (CE09436)
Also here
Rotary Encoder de-bounce with Nand gates
This might help.
Sorry not familiar with RPi or the several variations of Python.
Cheers Bob
