What's with France that these musicians must perform there?
To Congolese musician growing up, France was where all the "mythical" concert halls were; a mecca of sorts for them. It all started with Tabu Ley's Olympia in 1970, which is regarded as the first major concert ever with an African as the headlining artist.
It was at Olympia, where what would become "sebene" was created, as Ley wanted to speed up the pace of the music to make people dance and also apeal to the low attention span whites
Plus this is the home of the main diaspora fanbase, with plenty of donors and producers residing there.