SOPC Builder reports missing DB9000 Avalon components, but Quartus compilation does not

I am troubleshooting a legacy FPGA design in Quartus II 12.1 SP1 using SOPC Builder.During SOPC Builder system generation, I receive the following errors:
db9000avln_mstr_0: Component db9000avln_mstr 1.0 not found or could not be instantiated
db9000avln_slv_0: Component db9000avln_slv 1.0 not found or could not be instantiated

Additional errors report that the custom Avalon master has no waitrequest signal, cannot be connected to an SDRAM slave that supports backpressure, has a data-width mismatch, and has missing or invalid address-unit settings (SYMBOLS / WORDS).

I have located the generated db9000avln.vqm file and copies of the component PTF files. One important observation: although SOPC Builder reports these errors, the Quartus FPGA compilation flow does not report the same component-discovery and Avalon interface errors. I would like to understand the reason for this difference and the correct way to resolve it.

My questions are:
Why does SOPC Builder report that these components cannot be found or instantiated? Is this typically caused by missing component registration/metadata, an incompatible component definition, or something else?
Why can Quartus compilation proceed without reporting these errors? Could it be because the generated db9000avln.vqm netlist is already available and included directly in the Quartus project, allowing Quartus to compile the existing hardware implementation without regenerating the SOPC system?
If that is the case, does successful Quartus compilation mean the existing DB9000 logic is being compiled from the .vqm, while SOPC Builder is failing only when it tries to reconstruct or regenerate the system?
What is the correct way to restore SOPC Builder generation so that these components can be discovered and their Avalon interfaces validated?
How can I determine whether the reported waitrequest, data-width and address-unit errors reflect a genuine hardware-interface incompatibility or only incorrect/missing component metadata?

I want to preserve the existing hardware behavior and avoid unnecessary changes to the Avalon interfaces or generated netlist. So can I ignore the SOPC builder issues and move ahead with compilation and programming file generation in Quartus, will that have the functionality of the DB9000 IP implemented.

Thank you for your help.