How does the list of drawings get updated?

The  Drawings you see in Oracle Aconex Mobile (and in the web app) are a subset of the documents in the document register. 

By default, Drawings is defined by the below criteria but can be changed by your project administrator.

Document Type = “Drawing” or “Shop Drawing” or “As Built Drawing” or "Plan"

and:

Status = “For Construction” or “Issued for Construction” or “As-built”