On the Names and Languages of the Haradrim is a collection of 'Lore' published by the mod team alongside Update 34. This update greatly expanded the Near Harad faction and introduced some smaller reworkings to the other factions of Harad - the Morwaith and Taurethrim.
The document discusses the approach to creating the expanded Near Harad, which is largely non-canonical, but derived from canonical material. This includes information on the names and linguistic elements used in the Haradrim cultures. It also includes some history and backstory of the Taurethrim, which exists in a more complete form elsewhere.
If you appreciate the depth and curiosity of the Appendices to the Lord of the Rings, the Letters of J.R.R. Tolkien, and other such materials, and you want to see the mod's non-canonical material treated similarly, then this may be a read for you.
Note: the information contained in the document can be considered 'official' for the sake of the mod, but this information, like everything else in the mod, remains subject to change in future updates.