My understanding is that from the article, assembly was being done, not complete manufacturing. Which means that many of the components are imported components that are being assembled.
Parts from one country may get transported to another country to be built into a component, and returned to the original country for further assembly.
So it would be interesting to learn what the value of the individual components imported in is, and how much value is added by Indian made components and during India assembly and by Foxconn and Wistron.
Assembly is fine to start out with, but to bring more of the value add, one would need to build out an entire ecosystem of factories building the components.