rgrep adultborrower * | grep -v ^blib shows: circ/circulation.pl: $template->param( adultborrower => 1 ) if ( $borrower->{'category_type'} eq 'A' ); members/boraccount.pl:$template->param( adultborrower => 1 ) if ( $data->{'category_type'} eq 'A' ); members/moremember.pl: ( $template->param( adultborrower => 1 ) ) if ( $category_type eq 'A' || $category_type eq 'I' ); members/printfeercpt.pl:$template->param( adultborrower => 1 ) if ( $data->{'category_type'} eq 'A' ); etc. in several more places. There really should be a single function for this, or inconsistencies will creep in - note the 'A' or 'I' in moremember!
I can't find any mention of "adultborrower" in the codebase anymore. It appears that this has been cleaned up: Koha/Patron.pm:my $is_adult = $patron->is_adult