Hello,
2 points about leaders :
1/ leader losses :
They do happen, not often but they do, yet it seems to me that in the engine the probability is higher for corps/stack leaders than for division commanders as I have in each game lost a french corps leader in the first year to mid 1806 (once Soult, once Bernadotte and once Lasalle). I have lost a couple of division leaders but it seems to happen les often. I would probably lessen the stack/corps commanding loss risk by a third and double the risk for division leaders.
2/ leader promotions :
They happen way too fast for the french, might be due to the NM as well, but in spring 1806 one has easily had 15 generals promoted to 2* and 4/5 to 3* (Oudinot, Suchet, Saint Hilaire and Gouvion seem to happen very often). I would make it somewhat slower, say lower the probablity of being congratulated for example ?