I agree that it is an imperfect system. It does look like the skills were designed without Declarations in mind and then of attached later on. I can see why they didn't make it a pure FATE use, though, because FATE is also doing so many other things. And for any really powerful uses of declarations you're going to use FATE anyway - for example if you want an enemy's gun to jam you would have to use a FATE point because the roll for such a thing would be astronomical.
Most of the time people are so starved for FATE points that they would rather give up on, for example, getting into the house than spend a precious FATE. At least, that's how my players react to that kind of thing, even though I give out lots of compels to gain FATE as much as I can.
A simple solution (that goes into House Rules territory) would be a "Luck" skill that is purely used in declarations that don't have anything to do with another skill. When there isn't an obvious skill, you use Luck. This skill could also be used by the DM for random event and to gauge their general luckiness/unluckiness.
If we have experienced how thresholds work, is the effect only present while inside, or does it persist for a while after leaving also?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.