I’d like the header area of my site (2enews.com) to be responsive, but based on images populated in the header widget area. Enabling responsiveness in Nirvana settings seems to only apply to headers uploaded there, correct? Is it possible to have the responsiveness functionality recognize images in the header widget as well?
The theme cannot universally account for any kind of content that can be placed in the widget areas (including the header widget area). Those widgets should be responsive according to the existing styling provided by WordPress or plugins (if they are plugin-provided widgets), or their responsiveness needs to be accounted for manually if manual content (HTML) is uses.