Had a little time to take a look at the entries downloaded by the perl script and the .exe with the DLC. The perl script does download everything and has loads of duplicates. However, the .exe doesn't seem to download everything. I generated fresh .csv with both the perl and .exe.
Using Excel, I took a look at both files. I filtered out for unique content, and then compared the two files highlighting any duplicates so that the "missed" files would stand out. There were many entries not present in the .exe generated CSV such as:
Come Away With Me
Virtual Insanity
People Are People
etc...
I know that some songs are included in song packs, and some are standalone, but they should all carry unique IDs right? In any case, other content may be missed, but I only looked at one title. Is there something amiss?