Not sure if Possible.

So the system I have been making uses a d10 and a range of d6 for the hit. What I want to try and do is get the crit/fail of each of these dice to apply to the damage. But it needs to call a specific modifier to add or subtract damage from the roll. Where &{template:URPGS_Attack}{{name=@{AtkNm1}}}{{roll=[[@{Atk1}]]}}{{roll2=[[@{Dmg1}]]}} Is the current properties of the attack field. and critical success  needs to add +@{LucMod} and each failure needs to subtract -@{LucMod} And for that to not be tied into specific values but the actual crit.

Applying modifiers to damage rolls based on the results of another roll is not possible with the normal dice mechanics provided by Roll20, however, since you are a Pro subscriber, this could be done with the the API. If you aren't a Javascript programmer, you could ask for help on the API forum; there are a ton of talented people over there who help and sometimes will even do it for you.