Although variable WILDFLY_MODULEPATH is included in service configuration files in /etc/sysconfig/eap7-standalone|domain and /etc/opt/rh/eap7/wildfly/eap7-standalone|domain.conf, this variable has no effect neither on RHEL6 and RHEL7.

I guess that reason is that standalone|domain.sh starting script expects path to modules in JBOSS_MODULEPATH variable and WILDFLY_MODULEPATH is ignored by them completely.