Can you try to delete your settings.ini file before loading the game, then change the trasparency and see if it reverts back?
And tell us what you have done to revert back?
Sure can do.
Deleted file. Loaded up game and my latest save. Changed transparency to 100 (and UI animations to off). Replayed a memory - fully opaque as it should be. Played a round, got new customers (Nun and Sofia - really?) - fully opaque as it should be. Saved the game manually, played another round, both were happy but the transparency had changed back to 50 - UI animations stayed off though.
However, in the ini file it still says 100 this time.
Restarted the game, opacity was back to full when replaying a memory. or continuing the game. After saving it again went back to 50 in game (so half-see-through) but stayed at 100 in the ini.
Comparing it to the old ini (didn't really delete, just rename) it is otherwise the same except that the sound settings are unnecessarily precise (0.75 and 0.5 when I start up, 0.7535961 and 0.5036213, probably because I moved it back from 0 couple of times).
Then it started raining cats and dogs outside, but I guess that is unrelated.