Broken record here stuck on the same old groove. This fascination with "level". I've been riding 50 years and started racing 45 years ago. I've never leveled a seat. I adjust them until they fit right. For me, that is the most critical adjustment on the entire bike. I have 2-bolt seatposts on almost all my bikes so I can get that last little bit to perfect while on the road.
I've occasionally placed a level on the seat just for fun but would never use it to set a seat up unless I happened to remember "oh yeah, this seat happened to be dead level the front half when I laid the level on it two years ago". (Not very likely!)
Level seats are like 10D shoes. They might be "right" but they don't work for everybody! (My feet have been measured at 10D many times. Many of my shoes aren't. My feet rule here like my butt does on the bike.) Likewise, the saying when I raced was that God and Eddy Merckx rode 120 stems. I do on one bike (designed around a -17 120 so stems wouldn't be hard to find).