It's a good list because it gives both North Wales Welsh and South Wales Welsh terms. I think I said before that grandfather and grandmotehr are Nain and Taid in North Wales and not those listed by colcot.
I think that there are significant differences in the language between north and south. I recall a girl who joined my year in (a North Wales) secondary school and who was a fluent South Wales Welsh speaker, having to join the English -Welsh classes.
The mutations are the same though

Gadget