The player's record has apparantly been official knowledge in Zambia for a long time, just not been recognized internationally.
Cant help but think that its questionable to count records so far back from Africa anyway. Wasnt it the Zambian team in one WC during the 60s who didnt even know how a free kick / penalty was supposed to be executed properly?
If some micro-state like Fiji or Maui has a "top" league on the same level of Sunday football in other countries and some guy scores 120 goals over the course of 50 games there, should he be allowed the record? It would be a pointless record then, basically all about playing in the worst league rather than being the best goal scorer.
Mullers record was at least set in a time where football was a big deal and several greats were playing in one of the best leagues in the world. Messi broke that record under similar circumstances. This new "record" is set under very different circumstances.