The problem is that I use Sh IV 1.4. So I don't think I'll get a fix for the old RFB version...
Besides, I think I have found a solution. Using the Subschool torpedoattack mission I figured out that one has to add two additional knots to the targets speed (approached in a 90 degrees angel). So if one enters 10 knots into the TDC instead of the 8 knots the cruiser is actually running then it gets hit pretty exactly where one aimed at.
I already had to add 1 - 1,5 knots (depending on calm or heavy sea) to the Mk10 to make it hit in previous campaigns (without RFB). I think the Mk14 needs an additional 2-3 knots to hit its desired target.
I usually fire from a 90 degrees angel and a distance of less than 1000 yards.
But I only tested this briefly yesterday so this might not be accurate.