Oh boy, even after reading all of the hints, I could only solve it after downloading the patched version.
Spoiler, concern
One of the things that got me stuck at the very end was that I had to select Lorenz as the one who gave hush money, though it was done by Leon by Lorenz’s orders.
I still needed those hints because I was failing to understand why anyone but Jacek would have his own investment statement, but OK, I should have been more open to the possibility of document sharing among partners in crime.
It is a pretty well conceived game, in any case!