The ranges have been corrected for the upcoming patch. Bear in mind however that the exact position of impact will still vary slightly (up to around 2 or 3 metres in any direction) due to the projectile's inherent inaccuracy. Additionally, remember that changing your view pitch while using the mortar will change the launch angle of the projectile and therefore its trajectory, which will also impact the effective range.
So in short, you still won't necessarily be hitting exactly where you intend, but the margin of error should now only be up to about 5m, rather than a guaranteed 20-30m.