I think you have to decide what you mean by "level saddle." I find a saddle is most comfortable when it is dead level. But what is meant by level?
Does it mean that the saddle nose and the saddle back are at the same height?
Or does the saddle have a pronounced flat part that you want to make level, but the nose and back are then at different heights?
Or does the saddle have a "spoiler lip" that is meant to be higher than the front (like the old Concor saddles)?
Or do you level by "feel," making micro adjustments until you stop sliding forward or backward in the saddle on a level ride?
Or do you look at the bike in its entirety, and decide on an aesthetic basis when the saddle appears to be "right?"
Or do you have one of those seatposts that has a notched adjustment, so that the adjustment you want is in-between two notches?
Yes, getting the saddle "level" presents a greater difficulty than getting the handlebars "straight."
L.