Cleaning up SVG `transform="translate(dx,dy)"` in Inkscape
Here is the trick how to remove them:
Group the rectangles (Ctrl+G).
Ungroup the group (Ctrl+Shift+G).
Inkscape will then recompute the x and y attributes, incorporating the translate(dx,dy) defined in the transform attribute. Afterwards, the transform will then be removed.
PS: If I find the time to cleanup my presentation script, I will open-source it on Github.