Ralim would communication would vary. Initially he was more frequent asking ready to return with any stories or interesting items, but after Najila got a better hold of herself in the material plane, Ralim would likely get the hint that he may be asking too much. It would perhaps be at this that point that he bestows to her the Book of Clouds where there exists a divider where she can write how her travels in the material plane is going, which would satisfy him. But he may reach out around every other week to ask her of something. These things simply being a simple question or some assistance with something somewhere.

For how he communicates, it would be through the Books of Clouds. Just like how Najila can send stories of her travels, he can send her of things mentioned in the previous paragraph. She would know of when he sent such message when the nice sky blue thin divider fabric bowels on its own.