Lighter--

Thanks for the thoughts!

What you say here is what I'm thinking:

What Harlow and others may have done frequently is to try to reconstruct something imperfectly remembered from years before. They would innocently refer to printed versions to refresh their memory.

And with that, I wonder if we can get a sense of where/what print versions they may have used -- so as not to be misled by the narrative that stuff creates. I am, as you said, hoping to look at the field texts separately. To do that, we should know what are field texts. Well, Sharp, Carp, Doer are obvious, but there is too much valuable info in the chantyman-author texts to throw those out...unless somehow we can separate 'original' from 'derivative' within them. Perhaps not. But I do think that Harlow (we've discussed this before) contains much more that is derivative or "influenced" than is commonly supposed.
So, re: your statement,

In cases like this, my guess is that what's on the page approximates the theme of what was actually sung.

...while I believe that was true in some cases, I may be more skeptical. I will break down Harlow's verses, and see what you think.

I doubt that Harlow would call his own creation "doggerel."

True. I don't think it was his own creation. But more importantly, I don't think this statement is necessarily commenting on everything he'd just presented. Here is where I think he is (unconsciously?) echoing what he'd read.

Writing about chanties took on certain formulae; paradigmatic "slots" seemed to have been needed to be filled by many author each time something was written. One of these seems to have been to talk about hoe some shanties could be "mournful", and perhaps use Lowlands as an example. People who have read this stuff, when it comes time to present the song, would tend to use similar discourse.

I think "Landsman would think chanty texts were doggerel" is another cliche. My guess is that Harlow, not a great writer IMO, has rather clumsily chosen this moment to insert the cliche. The sentiment is sincere, but I don't read deeply into it in connection with his song text.