I'm seeing the same thing, but this was present in 0.912 as well (for Tireless March at least).  I think it's a feature of the difficulty level?  I was playing on Challenging.

Free bonus movement, free research, and free production is a reasonable way to beef up the AI at harder levels.  But if it's there at normal that's probably a bug?

Not sure either.  And now that I think about it, each AI didn't evenly cast the spells, which I would expect if it was a difficulty bonus.  One cast 4 enchantments on their capitol at turn 1, one cast 3, and the third cast just 1 or 2.  No idea how they paid the mana upkeep for it either, I think Relias had 6 or more enchantments up at turn 1 but didn't get a shard shrine until turn 16 or 17.