It is hard for us to provide assisstance without looking into to the case and doing some more invetigat work. Moreover as Ansys Employee, we do only provide high level guidnace on this forum.
There is no guarantee that both components of a compound observable improve. If you build a sum, only the (sum)-result must improve. If one of the components of the sum, outweights the other, it is even possible that one improves and the other one gets worse.
The alternative is a multi-objective optimization but due to the stiff nature of the optimization problem, you might not get a useful result at all.
We recommend doing a sensitivity analysis to understand in which high-sensitivity regions the observables are in conflict or support each other. That can give you hints why a multi-objective optimization does not work or why compound observables favor one of the components.
Good Luck!
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