Yes, ArB was indeed main assembly for He 177s (in numbers assembled). Allied Air Recon photos confirm the type there dispersed (images below are smaller than I saw). But as Arado FW originally comes from Rostock-Warnemunde there might be confusion there. Main thing is that ArB was ordered out of Ju 88 (wings) program into He 177s in 1942.
LFP only list assembly locations, not "actual production sites" (apologies for stressing that Production is not same as Production, term tends be used for assembly sites as well) .
There is still yet to make a book that covers this correctly.
https://de.wikipedia.org/wiki/Arado_Flugzeugwerke
http://www.8thafhs.com/maps.php?lat=...et_notes=Arado