I have been working on PSoC 5LP for a while, PSoC is quite powerful but it takes a lot of efforts to know the details... The DFB is another complex unit. I disassembled the FIR code generated by the Filter component, so I can test it with the DFB Assembler. I put some comments on it based on my understanding with the DFB module, I might be wrong... Here is the assembly code:
Nice work, code sure looks correct as well as the comments. I assume you have run the code through the simulator.
Of course for standard filters the Filter component is easier to use, but for special needs and making your own filter variants this is a good starting point.