This looks like… a simple bug?
Example source page: Surt del Cercle
Images are called with relative paths:
Resulting URL: http://surtdelcercle.cat/media/torbrowser.jpg (correct)
Imported page: Surt del Cercle - Surt del Cercle - Confederac.ió (notice the broken images)
The imported image URL: http://surtdelcercle.catmedia/torbrowser.jpg (broken)
Note the slash missing in “catmedia”.
I didn’t find a report for this bug, although this one might be related: Embedded topics don’t handle “//”-images properly
Can anyone reproduce? Or is there a fix that we could implement on our side? (other than defining images with absolute URLs, which we could do moving forward but what about the articles already published)