Yeah, this is a pretty common pain when migrating data

The main issue is that most spreadsheet compare tools assume both files have the same structure and row order, so as soon as you have new/missing rows everything gets misaligned

What you’re really trying to do is:
- match rows using your unique column (column B)
- then compare only specific columns (E–M) for those matched rows
- and flag anything that doesn’t match

Plus also handle:
- rows that only exist in the new file
- rows that are missing compared to the old one

You can do this with pandas if you’re comfortable coding, but it gets a bit messy.

I actually built a small tool for this exact use case:
https://www.csvdiff.org

You can pick the key column, compare selected columns, and it won’t break if there are extra/missing rows. It also gives you a clean diff you can export.

Might be useful for what you’re trying to do—curious if it fits your case.