So far: 'Naturalist' leader did not start by a mine (no mine visible at startup; found one a few turns later. How near is 'near'?). 'Warlord' leader did not appear to start with any extra units. Either of these might be a case of the tooltip being wrong (or my misunderstanding what it means).

In a game with a 'Thief' leader, the window after a multi-participant battle (4 vs 3) reported the extra gilders from leader ability in scientific notation ('9e1.2345'). Sorry, will try to reproduce and get a screenshot.