Artifact Reward Buildings

[Aluminum Elite Master]

This is something that's easy to miss, but if you combine 3 artifacts of the right set, you can unlock special buildings and other stuff now.

My question is: are these special buildings always the same for each sponsor? Because, as Polystralia, I got the very first building to be the warp spire, which if you look up is a fantastic reward for Hutama. More likely, I think this was dumb luck since from looking around, it seems like the reward is based off the set you get together and not what sponsor you are. But can anyone confirm this? I mean, it's a detail that's sort of big (special buildings and all) that didn't get a ton of mention anywhere prior to release.

[SamBC]

It depends on the artifacts, not the sponsor.

[Tzyder]

and you can get special nartion bonus as well as building

[atm]

I have had some incredible near game-breaking unlocks from artifacts - I am now spoiled for playing any other way.
My latest game, I was PAC and I managed to unlock two pretty cheap wonders that basically made me invincible - one that increased the rate of virtue aquisition by 100% (yes, it doubled the speed I got virtues...) and one that lowered all science costs by 30% (so I ended up with 30% more techs than I would have).

My only gripes are:
a) The AI is terrible at exploring. I expect this is because it constantly wars with the aliens and can't get its explorers across the sea-dragon infested seas. This means these benefits feel like they mostly only apply to the player and not the AI (which considering the bonuses the AI gets on hardest is maybe only fair, but still...).

b) Some of the unlocks seem to be utterly game-changing, like my double virtue speed. I think they need to throttle it back a bit, like make it a building that has to be built in each city, or something. Getting a single lucky combo can basically win you the game right from the start, which makes it less fun IMO. Most of the unlocks are actually fairly resonable, like improved city bombardment or increased capital from agreements - it's the overpowered few that have me scratching my head a bit.