Declined. I tested it and pyroblast damage is according to the calculations.
Screenshot: http://prnt.sc/b31adk
My SP is 13847. After 20 casts, recount shows: 29236 minimum damage and 29686 maximum damage.
[spoiler=Calculations](13847*1.98) + 1816 = 29233 min.
(13847*1.98) + 2305 = 29722 max.
Working as intended.