The only triple I have owned with an indexed front shifter is a 1994 Bridgestone MB-6. It is nearly stock, so the shifter, front derailleur and front crank are all from the same group, thus designed to play well with each other. I have no difficulty shifting it, but I often have to push the lever a hair beyond the stop to get it to shift well to the middle or small ring.

My other triple crank bikes do not have front derailleurs that are matched to the crank, I use friction downtube or friction bar end shifters and often have to over-shift a bit and then back off when shifting to the middle ring. I am used to doing that, it just takes an extra second to make the shift. On those three bikes I am using front derailers by Campy, Suntour and FSA, all three are designed for use on a double crank.

My road bike, A 2017(?) Raleigh Grand Prix has a Campy Veloce group with a double crank and double front derailleur, the front shifter is a triple. I bought a front triple derailleur for it so that I could put on a Campy triple that I have in storage on the bike, but before I got around to that I learned that the derailleur was designed for a 39T middle ring and my Campy triple has a 42T middle ring. So, I never tried to install that in anticipation that it would not work well.