I do recognise some Mtarfa colourways amongst those - so Mtarfa is the most likely after all.
(Although I'd like to see a marked piece in this colourway, in a different shape, to be 100% sure.)
I don't know how to condense a link to a search. I deleted the JIP bit of David's search and plugged in "signature" instead. Some odd, crude marks did appear, which might be similar to this one?
I can only ask others to do the same, and try to see if they can compare the squiggle. I can't compare squiggles because of short term memory problems. By the time I look at the second thing, I've forgotten what the first one looks like.