Hi There,
That Cornerstone is a Cloud Application, it is a different platform and not for WordPress. And no it wont make any difference with regards to your background-image issue.
Background-image is responsive in a different way please see this link on how background-image works. The default behavior of background-image is the cover, the image will try to cover the entire section/container by expanding itself resulting some parts of it may not be visible within the container. You can force the background-image to always fit to its container by adding the background-size:100% 100%; on the section’s STYLE field, but that will squeeze and stretch your background-image on some screen-sizes specifically on mobile phones. Have you seen your background-image on mobile?
If you need to emphasize those images then do not add it as a background, but an Image element so it will fit on the container regardless of the screen width.
I suspect you have a larger screen, because on our end the heads are not cut-off. You can add background-position: top center; on your section’s STYLE field and it will always show the upper part of the image.
Hope this shed some lights,
Cheers!