I came across this thread just now, and am thrilled to see the
lyrics of the 1804 broadside - thanks so much, Martin Ryan, for posting it. I have been singing the song with pleasure for 10 years or more (having learned it from the Mary Ann Carolan recording) and it's always well received. Some observations on the MAC (standard) version:

For those who are struggling to make sense of
"There I saw two tinkers dividing a saucepan, although they were arguing about a tin can"
I believe that "dividing a saucepan" means drinking a saucepan of
porter (one presumes) between them, the good stuff having been dispensed in less convenient containers in those times.

"about it in cant" is clever and of course makes much more sense,
but having tried it out a few times to myself, I'm not gone on
the plosive -nt ending.

To a recent query about "fancible", it seems to be a local word
based on the noun fancy as in "she's my fancy" i.e. the girl I desire.

I have no difficulties associating "pitcher" with cream (or milk)
i.e. a pitcher may be used for holding other than alcoholic liquids!

Someone mentioned out to me that instead of "beside Donegal"
"beside Cushendall" (a picturesque north Antrim village) has also been heard.

Padraig