The Eternal Flame cannot be constructed until Elementalism, but you can get it sooner through a Clan-only option on the non-uncommon meteor event. I once got lucky enough to get the event on the second turn of a game. The event can also recur. It let me have Eternal Flames in three different cities once.
Bhall Orcs also get a free promotion pick from each source of Fire mana and have Fire affinity, so they are still valuable.
Th upgrade path issues are related to <bDisableUpgradeTo>1</bDisableUpgradeTo> tag that Ogres have, which Kael put there to prevent Orcs from changing races to Ogres. No unit can upgrade to any unit with that tag, no matter what upgrade paths I set.
Tholal's code limiting upgrades that change racial promotions could also be an issue.
I never really liked it when Kael changed Ogres and Stoneskin Ogres to work as they do now. I have considered going back to his earlier implementation where Ogres replace the mounted line and the Clan has normal Champions o