In fact you are right, if the top is bended that will cause the guitar to be out of tune.
I exemplify that problem you are talking about on minute 6:00 of this video:
The only repair for that extreme problem on the top is to change it and re-fret the guitar again, which is like a heart transplant. This is not very advisable because of two reasons:
1) It's not sure that the guitar can come “back to life”
2) To perform that repair properly will cost at least 1,200 euro.
Many people wrote to me saying similar things and, in the best cases, they end up selling their defective guitar and buying a proper one.
This tuning feature is really an issue because is not a good idea to continue practicing or playing with a guitar that does not even tune well.
As you know the fretboard is divided into 4 main zones to consider in this regard, namely:
I) From 1st fret to the 4th fret.
II) From the 5th fret to the 8th fret.
III) From the 9th fret to the 12th fret.
IV) From the 13th fret to the 16th fret.
The weakest zones in guitars with poor calibration of the fretboard and setting of the top are I and IV, while in bended ones are generally more evident in zones II & III.
I hope this information will be helpful to you.