Linux changed a bit naming of the variables, and some variables currently listed depend on other which are NOT listed in the ebuild checks. Therefore, if one want to enable those missing one just cannot find them in .config because their upstream variables were not enabled and hence the downstream tree is not expanded in .config. so, it makes sense to include checks for the upstream variables.
My experience with lnux-4.14.15. I think the below reenaming happened but please double-check my guess is correct:
CONFIG_NET_CLS_CGROUP is now CONFIG_CGROUP_NET_CLASSID
CONFIG_NF_NAT is now CONFIG_IP_NF_NAT
Add introduce checks for:
I do not see CONFIG_IPVLAN and did not dig deep enough to figure out which upstream entry is disabled.