Spectrum Profile edit method?

Hi,

My question is what method is behind the Spectrum edit mode in Pro version for realistically fine tuning the piano sound? Is it just about everything by hearing like "seems I like this more and this just not so"? Hardly believe so. Maybe some reading available about this? Some software such as Sony SpectraLayers or Izotope RX 5 could be used for analyzing or comparing with a real recorded note samples? And again even with "by hearing" method there should be at least some kind of procedure for it?