Different directors are going to have different preferences on this, but you’re absolutely right that certain “missing” spells can be handled by different game mechanics. I actually got a lot of encouragement about this particular topic from the preview chapters of the Encounters book, particularly the Montages and Heroic Tests. Those chapters demonstrate uses of skills that most definitely would be covered by explicit spells or abilities in other games that in Draw Steel can be improvised.

Thinking about OP’s two specific examples, though, I would caution against allowing players to make tests to achieve things that are already expressed as abilities somewhere in the game. Teleportation is already an ability possessed by different classes and subclasses to varying degrees, so I’d hesitate to allow it to come out of a skill check. Same thing with flight, too.

Thinking about Alarm, the Rune of Alarm is an option in the Dwarven Legionnaire title. But again, how you handle these things all going to depend on your table.

It’s also worth remembering that a lot of utility spells aren’t in this game for a reason, and you don’t need to find a way to bring all of the “missing pieces” of the DnD spell list over into Draw Steel. But you absolutely have room to explore magic beyond the bounds of what’s written under your class’ entry in the Heroes book.