The Spirituals actually had a very hard time progressing their Forces. The trouble was that it was a matter of relativity.
The Spirituals had exceptionally high affinity, but in comparison their progress was slow. Due to this, while they seemed to be much faster than other Mortal Races, if this ratio was taken into account, they were actually quite a bit slower.
Leonel's progress was the perfect benchmark for this. It had only been three years at most since he learned about Force Manipulation and the levels of Forces, and yet in that time he had gone from an Unfurled State, through the Impetus States and now had a hoard of Life State Forces at his beck and call.
Of course, not every Spiritual had affinity as high as Leonel's own, that was ridiculous. However, at least in some aspects, they were certainly his match.