In my opinion there are few composers who have been very good at orchestration namely Salil Chaudhary, of course the one & only R D Burman & the living legend Ilaya Raja.
To bring about a good orchestration one needs to have descent understanding of a wide range of instruments, musical intelligence to innovate and use them in an effective way & brilliant sense of sound mixing..it doesn't matter if this concept is Indian or Western, Hindi music has taken influence from several sources notably Persian & Central Asian culture.
For that matter we should stop listening to & playing tabla (name itself derived rom an Arabic word tabl..), Harmonium and many other instruments because they are not Indian, this is a never ending debate but my view is that any effect which is pleasant & improves ras & ranjakta of music is welcome.
Now about Kalyanji & Anadji's music: as has been said many times , RDB hardly left any thing for next gen composers, he did so much of work in music. He was the first to use electric Bass guitar in dum maro dum, he introduced use of synthesizers in a big way, when he sat at tabla it rose to a different level, be it use of tabla tarang or producing takum effect in songs like roz roz aankho tale (now I learn that this effect is a composite effect of duggi & madal; this was a very important instrument for Pancham to complete the matra in laya..he was also using brass section in a diff way, hmm I would say it was quite Jazz style of using brass. I don't want to get into the string instruments used by him as he was a prolific player of sarod and used all sort of guitars & gizmos associated (like flanger, distortion, wawa in a brilliant way)
Let me tell you that if it was not bassist Tony Vaz with Pancham many of his songs would not have had the same effect ( he passed away only recently).
Usually it is possible to identify the songs of RDB because of these signatures & style pattern, I would identify RD's song even if I'm under anaesthesia.
Kalyanji Anandji used musical instruments in a diff way from Pancahm, of course it sounds similar but they has their own style, listen to their rhythm effect : it is quite diff from RD's. KAji were very fond of triple & bongo and often tuned them to diff notes. His sound mixing is also quite diff from Pancham's & there are other telltale signs as well…..