[LDiCesare]

I don't know if there were changes in latest CBM to the summons, but basically demons of heavenly rivers are sacred berserkers who kick ***, and demons of heavenly fire are extremely powerful flying fireball throwers that your flying celestial masters can move along the map as they like.
Planning a 125% shock resistance is a nice idea, but that won't be very helpful since that will only help capital-only commanders.

Regarding archers, TC archers are expensive, but their bows are composite bow, so I would say they are inferior to Sauromatians and Kailasa (but the latter are expensive in gold). Maybe Yomi's aka-oni if you see them as firethrowers. Otherwise, they are rather better than average.
Ulm has warrior maidens: short bow/prot 11 for 11 res or prot 4 for 4 resources.
Sauromatia has composite bow/prot 4 for 7 resources, and poison archers.
TC has prot 9 composite bow for 14 resources. Plus a good helmet.
Caelum has short bow plus prot 5 or 7 for 5 or 9 resources.
Kailasa has 9 gold/3 resources prot 1 shortbows and 20 gold/10 resources prot 3 9 precision longbows plus sacred longbowmen.
Yomi has 9 gold/2 resources prot 2 shortbows.

Composite bows are precision 1, have a range of 30, deal 12 damage. They are far better than any other bow in this era, except for poison bows and sacred Kailasa bowmen. The ape longbows are twice as expensive and have crap precision (9 vs 10+1).
Overall, I'd say TC archers are not very massable but are the best in the era.