I’ve run into a number of issues trying to reconcile JSFL and compiled clips. Some of the features of a library object are unavailable when inspecting a compiled clip, leading to the wonderful JavaScript Errors we’ve come to love.
The particular oddity I’ve been wrestling with is that CompiledClipInstance objects don’t have a timeline, so if I try and walk the display list, digging into items as I find them, when I hit one of these, the reference to instance.timeline throws an error. The only solution is to exclude these kinds of items from your search.