Thanks to Marie Beleyme, we now have answers to our two sculpture puzzles.
The large relief, dated 1829, in D39 is the grave of Cappon/Capron/Carron, the spelling is unclear at this point.
(all photos from Pierre-Yves Beaudoin, wikimedia)
In D6 the eroded stone with the relief of an eagle on both sides is in fact part of the original monument to the Memorial to the Victims of June, which is located close by. As you can see from the monument itself it, too, has the same eagle relief and you can now make out the words liberte ordre public.
The puzzle and its answer: