Should probably read: "Steam-powered — Search your library for up to two artifact cards, reveal them, and put them into your hand. Then shuffle your library. If only colorless mana was spent to cast this spell, instead search your library for up to two artifact cards, put them onto the battlefield, then shuffle your library."

Steam Powered is kind of like Kicker... the player needs to know fully what to do before seeing the if clause if they happen to not have the spell be steam powered. See Primal Growth for a perfect example involving searching and shuffling of libraries.

I feel like this should actually just be worded like tooth and nail:

Search for two artifacts, reveal them and put them into your hand. then shuffle.

Steampowered - If only colorless was spent to cast this, put two artifacts from your hand onto the battlefield.

Steam-powere dis a keyword, and probably does need to be first. The revision I suggested does match an actual card that does want to be doing the exact same thing- search and put in hand normal, instead search and put into play if kicked- and the card's oracle wording has not changed, so my gut feeling is that it's the best way to phrase it. Some of the Steam-owered cards are tricky, like the one you can cast with flash, but I feel like the wording I recommended fits the best.

"Steampowered - If only colorless was spent to cast this, put two artifacts from your hand onto the battlefield." might be confusing since opponents might assume that you can't search for two artifacts first.

With this card, since Steam-powered's effect is doing the same thing as Kicker, it can't hrut to use the exact same wording as a previously existing card with Kicker.

True, but the card is modeled after Tooth and Nail, and I think the added functionality of putting out any artifacts you have, not just the ones you searched for, makes the card better. (You avoid awkward situations where your win cons were already in your hand)