And there's the rub. The confusion between a modern or ancient Folk process, and the reporting/collecting from that process.
Bert could and did sing what he liked how he liked with the words he liked, same as the rest of us. We swiped his songs right left and centre. so far no problem.
When you become a collector,and remember I've been there, you report what you find, as well as you know how. Rewrite songs if you want to sing them by all means but publish the originals with honesty.
Bert didn't. Problems begin. It's as simple and difficult as that.