Something that sometimes stumps people that have read lots of Greg’s deep background material is that many Gloranthan deities have more than one name. Despite this, they are still the same entity and can be worshiped and contacted under both names (and often are).
Thus Orlanth is known as Umatum, Lanatum, Thunderous, Adventurous, and Rex. Yelm is known as Somash, Yu-Kargzant, and Ehilm. Lhankor Mhy is also known as Buserian. Shargash is also known as Tolat. Yelmalio is known as Kargzant and Elmal. And so on.
Where possible, writers stick to the common accepted names – Orlanth, Yelm, Lhankor Mhy, Shargash, Yelmalio, etc. – rather than use a local name.
So for example, Lhankor Mhy is the god of literacy and knowledge. He’s called Lhankor Mhy in many lands. However, in Dara Happa, he’s commonly called Buserian (“learned one”) and his initiates are called buseri or “learned ones”. But they are the same god, with the same Rune magic, and the same basic cult structure.
I think this is related to the difficulty many people have in accepting that the Gloranthan are not cultural constructs. Their cults are (indeed cult is the source of the word culture) but the subject of the cult is eternal. Occasionally, worshipers experience new things about their gods, which changes the cult. But the god was already there.