@Fer I don't believe there's a way to modify that, but why not just add a sublist to the Vendor/Customer Record which lists the same data and you can then add extra columns as needed

Having the sublist view, I already added whatever filters might help them. But let's say they want to download that sublist do you know if there is a way to add a download excel/pdf/csv option to the sublist. Or at the very list a link to the saved search with the filtered criteria?

No, you just get the list. I'd be tempted to learn from them why they need to download the data, once it's downloaded it's not longer live data, it loses a lot of it's value and obviously adds security issues. If they absolutely need to, just add an Inline HTML custom field with the URL to link to the search

Mostly because our operation is massive, specially with our vendors, sometimes looking at 50/100/500 results on a browser isn't as effective as being able to have the 50 000 results in an excel and just manipulate it from there.