Changing spell parameters for Pathfinder 1E game

I've got an NPC Draconic bloodline sorcerer who gets to add 2 damage per dice on fire element spells. Trying to get their spells set up to just take double the caster level and limit it to whatever the dice limit is normally, say 5 for Burning Hands. Experimenting hasn't gotten me where I want; I can just punch the amount in manually, and it works, but when I get more automated the spell breaks.

Something like this would give you "double the caster level" with an upper limit of 5.  (attribute name and how leverage the macro will depend on which sheet you are using...) [[ {[[@{caster_level}*2]],5}kl1 ]]