Is there an official scene where they show those cutiemarks?

@Mashni
No, the Wonderbolts are never seen without their flight suits, so their actual cutie marks are never seen.

Soarin’s is actually the cutie mark shown on all stallion’s flight suits. Spitfire’s is never depicted in the show, all you ever see is the lightning bolt shown on all mare’s flight suits.

Thunderlane and Lightning Bolt both also have lightning bolts for cutie marks.