Apenas uma chamada para o awk:
$ awk -vOFS='\t' '
/^group/{group=$1;level=$3};
$1=="name" && $2!="nickname" {name=$2};
$2=="nickname"{o[++i]=gensub(/member/,"",1,$3)" "name" " group" " level};
END{
asort(o,p,"@val_num_asc");
for(i in p){print "member-"p[i]}
}' file
member-0 sanders1 group1 1
member-1 sanders2 group1 1
member-2 sanders3 group1 1
member-3 sanders4 group1 1
member-4 Matty1 group0 1
member-5 Kendal1 group2 2
member-6 colen1 group3 2
member-7 colen2 group3 2
member-8 colen3 group3 2
member-14 Matty2 group0 1
member-15 Kendal2 group2 2