Mmh, what is the infra-level of Berlin and Tübingen in your game?
Just to be sure I've retested it with DH full (1.05.1, checksum:YEXY), 1933 Germany (my checksum differs from vanilla DH, perhaps due to images or whatever, so I also retested with a new install with the approbiate vanilla checksum:
KVZZ... there was no difference, though):
100% infra: Berlin => 487 days
90%: Potsdam => 492 days (+5)
80%: Aachen => 499 days (+12)
70%: Erfurt => 507 days (+20)
60%: Rostock => 519 days (+32)
50%: Konstanz => 535 days (+48)
40%: Tübingen => 559 days (+72)
And I got this:
View attachment 731711
So, I am not sure why your results differ.
... some time later...
I kept on testing... and I also noticed that your production image shows some progress already done and thus I did the same: let the game run for a bit and:
You are right! I am wrong.
What happend...
Initially production times differ according to the infra-level (espcially if you stop the game, as can be clearly seen in above image) but after you restart the game, latest after the midnight tick, all production times change and get aligned with each other. Then infra doesn't matter anymore and building eg 1 IC takes the same time in a 100% or 40% infra region. Perhaps different production times according to the regional infra level were once intended but then either not fully implemented or even overwritten again. Or the other way arund, it was intended but not properly implemented and some old code overwrites it.
Now I need to change my building patterns and behaviour because I've never noticed that the production times rechange again.
Actually kind of a pity that it doesn't work as i thought (and is initially shown), it would had put some some more meaning and importance to infrastructure.