Thank you for the detailed explanation. I fully understand that for each sruthi it is better to go for the right mirundangam vaagu.
I would like to rephrase my question.
During group singing like Thyagrajar aradhana , I was told that a mirudangam with pitch 1 1/2 that is c# can also suit for
people singing in 4 1/2 that is f#. some setiings like panchamam or madhyamam. I was also told though people singing in F# may not find this disturbing but they will
not be comfortable when they are singing songs with Pa or Ma note. I do not recall which one.
When you do not have any alternative mirudangam, how to increase or decrease say by half pitch to support singers pitch.
if it can be explained like following table ( it is only a representation may not be right also )
Mirudangam Sruthi Singers Sruthi
1 ( panchamam ) 5