First the general stuff: My initial impression is that I really like the theme. Heavy duty Caelum, trading mainline evocational access and resistances for tough-nosed recruitables. Like Humakty pointed out, there's definitely a lot of firepower and certain things, most notable the trolls, but there's a lot of weaknesses to balance it out. The best mage suffering from old age is a great counterweight, and I might think about bumping up the starting age just a little bit more. You'll also have to steer pretty clear of a lot of classic Caelum battlemagic (looking at thunderstrike here) since pretty much all of your troops close quickly, either due to decent movement rates or flying, and wind up prone to getting friendly fired. That all makes for a balancing act on the battlefield that I really like.
On to the details: Trolls do seem just too good. 5 of the basic model can roll over any non-heavy cav indy without losses. That makes for a blistering initial expansion without any reliance on blessings. About the time that heavy battle magic comes around to stop them, you're leveraging their good inherent MR, mass flight, darkness, elemental resist buffs et al and still brutalizing people. A few quick ideas are a map move decreases, dropping the second attack or their base attack value (I like the shield bash for thematic reasons), an MR drop, and making the elites cap only.
A combination of cheap forts and an army transport spell that uses earth gems and can be cast pretty much out-of-the-box by a recruit anywhere mage with high leadership gives them a really frightening defensive capability. It's hard to experiment with that one, but given the tremendous amount of earth gems you're likely to have around, this might merit a tweak.
Paying gems for a never healing unit makes me sad. Switching the troll kings to magic units and costing them accordingly is something I'd like to see as a player. I also don't understand the high encumbrance + reinvigoration that they have. Am I missing something? As for the undead sacreds .. I'm not sure. I don't think I'd ever spend death gems and a mage turn on them as is, but I also don't have any positive feedback on the unit, so grain of salt and all that.
Harab Seraphs seem kind of superfluous in the line up, but they're about the only unit that does.
10 astral gems for an Eagle King is a steal for anyone, but especially for a nation lacking in quality thugs .. maybe up this price a little?
Finally, recruitable stealthy units without access to a stealthy leader has always been a peeve of mine.
All in all, it looks like the outline of a very fun, flexible and different nation. It's Caelum, only playing in the NFC East!*
*a conference known for its grueling, hard-nosed, smashmouth style of play, for the 95% of the world who doesn't care about American Football