The collapsed section is not accessible but Geis does indicate there is a hidden door that likely was ruined during the collapse that would have led to that room. The hidden door is well concealed and very durable so now is just another wall.
Geis helps with the searching, starting with the two slain leaders. The outer room has a variety of miscellaneous items but only the two slain hobgoblins have anything of real use for Skeeves plan a bit of light spell work can clean and patch the cloaks
[ +- ] Inner Room Contents
4 Vials, Hammer, Shovel, large egg x3, Waterskin, dried meat, short sword, wooden shield, 3darts, leather armor, iron key, pendant, boots, gold x197, silver x60, copper x1600
[ +- ] Outer Room Content
ale recipe, Quarterstaff, Morningstar, a small wooden cask of ale, a violet glass eye, a single copper chess piece, hooded Lantern, war axe, iron pot, hubs
2x Hobgoblin gear : Chainmail, longbow, longsword, shield, boots, tunic, cloaks, belt, pouch w/12gp
One had a sack with linen bandage, a set of playing cards, a ivory pair of eating utensils, and 7 amethysts.
Mage
Robes, Scarlet dagger, Gloves, Staff, tunic, boots.
Bugbear
Warmace, Gauntlets, a scrap of vellum, Belt, Bracers
After digging through the other room you do find the sealed chest shoved under a pile of rags and miscellaneous junk next to the mages bed.
OOC:
Items easily identified as magical by touch are now in underlined
Other that that there are other miscellaneous items but nothing stands out as of value or use