There's no official statement. Technically they are all considered the same expansion. The Cult, released via Spielbox, was the public release version for people who already owned the other expansions included in Count, King & Cult. Cult, Siege & Creativity, meanwhile, was the English Rio Grande Games release. They never released King, Count & Cult in the US, only Z-Man did, and Z-Man did not release Cult, Siege & Creativity. There's no official statement about mixing them together because officially, there is only one version of the expansion.
The same applies with Cathars/Siege/Besiegers using almost the exact same situation. (Spielbox released Cathars, followed by Rio Grande's release of Cult, Siege & Creativity, ending with Hans im Glück's release of Besiegers, which technically is the first official release of that expansion.)