Do you have
an error display running? If not, go get one. If there is an error, it probably tells you exactly what and where the problem is; if you need help deciphering it, post the error.
Have you tried adding
print statements to see what's happening in realtime? I'd suggest adding one in Auras_PostUpdate (Functions.lua, line 509) as a first step.
Both of those are basic troubleshooting steps you should always try first.
Offhand I'd guess your problem is that your debuffs container frame simply isn't visible, because you don't give it a position (using SetPoint) or a width (using either SetHeight for an explicit width, or multiple SetPoint calls for an implicit width). If you want the debuffs to be in a fixed position, you should copy from the "party" section instead of the "target" section, and just change which CustomFilter it uses. If you want the debuffs to be moved or otherwise reconfigured when you switch specs, you need to copy the
entire "target" section, including the "UpdateAurasForRole" function (remove the part of it that concerns buffs) and the "RegisterForRoleChange" method call.