So in that screenshot, you can see the test-midi-files output for the original file on the left, and my modified file on the right. If there are new lines in the text file, it colors them green. It also marks differences in similar lines around it.
So in that screenshot, I should have had a Bank Select MSB and Bank Select LSB in both of the green areas. But my positioning was off with some of my code, so the results came out unexpected for the first one (Bank MSB, Undefined, General Purpose Controller)
Unfortunately, with the byte offset added in to the text files now, it's much harder for the plugin to track these differences, and I copied over the previous install of test-midi-files, so I no longer have it

So having it as an option instead of always on (maybe an option to disable it but leave it on by default, like --nobyteoffset) would help if I need to do future comparisons.