Richie
If you look at p225 you'll see Child acknowledges the birben/brirben differences. Presumably what he is saying is in the ms it is 'brirben' and in A&MSS it is 'corrected?' to 'birben'.

If you look in the glossary in vol 5 you'll see Finlay had 'birchen' which of course in Scots would be 'birken'. A handwritten copy could easily mistake 'birken' for 'birben'. The comb to me was obviously made of birch.

As for 'cored', well, nobody's ferpect!