Dot's meaning is near enough. The word written is probably 'ferunt' not 'feurunt' (which doesn't exist). "The congregation bring within [name of child]" i.e "The congregation bring [the child] into their number" which is tantamount to ' they welcome the child to the congregation', isn't it?
Latin used in churches was a bit removed from classical Latin: clerical Latin developed its own vocabulary and usage.Celebrata must mean 'congregation' and be such a word . It seems to be a noun ,formed in the neuter plural,governing the third person plural 'ferunt' and derived from the verb meaning to go to a place in great numbers' and also 'to go in great numbers to a celebration, to keep a festival, to solemnise en masse'