In the ULP directory you'll find an ULP named "check-used-lbrs". This ULP checks for missing or renamed libraries.
However, there is a bug which makes it completely useless.
Replace the line:
if (name == LbrName[n]) return -1; // LBR in lirary list.
with:
if ((name + ".lbr") == LbrName[n]) return -1; // LBR in lirary list.
Now it will check for, and report missing libraries.
Best Regards,
Joop