Altera FFT - output scaling. How to do this correctly?

I checked your inputs in matlab. All is ok if you scale the output by 2.

for example amplitude given by matlab fft for your input is 29569 which is pretty close to double your first example result.

Now you proved that the problem is indeed to do with fft IP scaling, that is what you started with anyway(-10 should be -1). You now either cautiously use your workaround of rescaling (exp=exp+9) and wait for other people on the form to respond with their experience or ask Altera for help.