Referencing a global variable in a custom formula

I’m trying to build a weighting matrix for prioritising our agile roadmap in ASANA, rather than GSheets, and it would be useful to be able to reference global variables rather than hard coding % weightings into the formula itself.

So: Each dev solution task has a (Customer Value, Commercial Value, Effort Value, Risk Value).
It would be great to be able to build a formula that does this:

((Customer Value x var 1 %) + (Commercial Value x var 2 %) + (Effort Value x var 3 %) + (Risk Value x var 4 %)) x (Problem var % Weighting) = Score

Hence, the variables need to be able to be referenced from somewhere else not in the task itself, perhaps another tasks that could be updated independently?

Users must be doing something like this already… any workarounds? Or just hard code?