I'm a bit surprised. Usually people here always ask for realism, but it seems no one cares about the extremely unrealistic 'perfect' spy-log. Making accurate claims was quite difficult and over-claiming happened a lot, especially later in the war when there was little time for confirming anything. Just look for Albrecht Brandi.
I'm wondering whether the mod is too difficult to install or too difficult to use
Or is the basic idea too drastic
If it is too extreme/difficult one can also just hide the log book and the total tonnage and the player then has to guess only the tonnage, not also the number of ships sunk.