Does a toilet have to be level front to back if the toilet doesn't rock and the flange tilts too?
There are purists out there that may say it must be level, but if it looks good setting there, I would let it set on the floor with no shims. It should not affect the operation of the flapper or valve that flushes the toilet. I would rather see a consistent caulk line at the base of the toilet than it setting level in both directions and have a huge joint in front.