adash, the color reversible process, as in fact all processes of photochemical processing, it is important that you get black and white. The remaining intermediate tones will come by itself.
For this it is best to use a gray scale test.
In reversible processes (b & w and color) first development is the most important.
The images do not see any black (perforation film). Is down the black from my eye. Time or temperature change at the first developer until you get a good black.
Chromogen developer dilution will lead to a decrease in the final image contrast.
In your images I see a low contrast, so an increase in chromogen development time will make the image more contrast.
Orwo films were made for cold processes (20-25 ° C).
It is better and easier to do tests at room temperature, with prolonged time, especially in the two develators.
It may be that your films are too old and can not get results from your expectations
See that was posted on APUG about working in C 41at 20 ° C.
Development time is ~ 10 minutes???
My scanner not work and I can not put the processes and recipes from Orwo now.
Again, I think you can get better results if processed film UT 18 or UK 17 like color negative process, using different chromogens revelators from C 41 or E 6.