About who made that “set”, it’s really not a “set” in the usual sense.
Modern Gaida players often play without drone, so the instrument is the chanter (gaidunitsa).
Professional gaidari travel about with a number of chanters in various keys so as to be able to perform any music they need to. They’ll have a single bag, with corked off drone stock, to play all their chanters in.
I took lessons for a year from Georgi Doichev. He had seven or eight chanters to cover all the keys. I bought the biggest chanter, the Do, and the next-highest, the Fa, from him. The Do (bellnote C, tonic G) was of an unknown make and probably from the 1940s according to Georgi. Georgi said that that pitch was quite rare. That was a fantastic-playing chanter with interesting bone rings. The Fa chanter is more modern but that’s also an unusual key, bellnote F, tonic C.
The Sol chanter is by Kostadin Varimezov, the Re chanter by an unknown maker. Later I got a Re chanter by Hector Bezanis (the great American gaida player and maker). Georgi was able to sell me those two unusual chanters because Hector was making him a complete set in all the keys.
By the way, all four chanters are in the same wood, what the Bulgarians call dogwood. The Varimezov Sol chanter is stained, as dogwood Bulgarian gaidas and kavals often are.
The basis of the drone was a Varimezov G drone. I had somebody make me various sections so that I could have a drone for all of the four chanters.
I played all four chanters on a regular basis in the International Folk Dance band I used to play in. It’s because the singers had to do various songs in certain keys to suit their voices. Hector said I was crazy, maintaining four chanters in tune like that.
Not only does the Kaba Gaida use different nomenclature for naming chanter pitch, the Kaba Gaida drone uses a different harmonic than the normal Gaida drone does.