RPG is like Star Wars Legends. Used to be semi-canonical, until decision was made to get rid of it (most likely to make lore less convoluted, because there were ton of weird things in there...for example, half-elven daughter of Daelin Proudmoore) and now cannot be seen as canon. Of course, there can be things brought from RPG into the canon (just like Thrawn, Old Republic style ships and so on in Star Wars), but unless stated otherwise, information from Chronicle is just as canon as fanfiction about Arthas and Malfurion on Deviantart (I hope there is no such thing, but I am most likely wrong).
Obviously it can be used as good source of information if you want to fill the blank spots, for example names of other settlements on Kul Tiras besides Kul Tiras itself, but at least to me it seems as if RPG is the main source of lore in this mod, with games, books and Chronicle being only secondary.
Obviously it can be used as good source of information if you want to fill the blank spots, for example names of other settlements on Kul Tiras besides Kul Tiras itself, but at least to me it seems as if RPG is the main source of lore in this mod, with games, books and Chronicle being only secondary.