Small correction - the sf & ef formula is actually:
260*(energy+10)/(250+energy) + min[ energy*ef/15000 + strength*sf/15000, 200 ]
for all "spells".
Two things to note: 1) Most of the time sf = 0, so the second fraction in the square brackets is zero which gives you the formula in the docs. 2) The effect of ef & sf combined is weighted equally and capped at 200. The contribution of energy (first fraction) is capped at 260 asymptotically.
Bonus: calling the result of the above formula "spell damage" is wrong since it's actually a separate global multiplier to your spell damage. A "more" multiplier if you will, for those of you familiar with PoE terminology.