The change I made to the Lens plugin was support for OJS based artwork files. In order to make those work, you need to apply a patch here: Allow artwork files for XML galleys by ajnyga · Pull Request #1353 · pkp/ojs · GitHub
After that patch you can add the images to the XML galley and IF the XML galley file has references to image files with the exact same name (just the file name, no path), the lensGalley plugin will rewrite those file paths and show the images you added to OJS. This is the same function as with HTML galleys.
The default setting in lensGally is that it will show images with full URL’s, so adding the images to another accessible folder and linking there will of course work. This was however something that I thought many editors will not want to do, or can not do.