Thank you for including the screenshot, @SteveDelFante. The Canvas Credentials Guides document Comparing Canvas Badges Basic and Canvas Credentials lists that there are 9 certificate templates with Canvas Credentials, which it looks like you have based on your screenshot (Canvas Badges only has 1 certificate template). I don't see an option for making those editable. I checked my issuers and noticed that the colors for the elements in the various templates do not change, even when the badge itself has a different dominant color.
I think the badge itself is the best place to include a logo, but editing the templates is an excellent suggestion for an improvement to Canvas Credentials/Badges. Please visit the pageHow do Ideas and Themes work in the Instructure Community? to contribute your idea to make Canvas Credentials/Badges better.
Creating an idea does not provide an immediate solution to the problem you described, though it is a solution. I’m going to mark it as such and hope that our colleagues who have a similar challenge will find the best way to contribute. If you decide to create an idea, please link it here.