This enhancement is from Adaxa. We are pulling same from adaxa and trying to explain requirement here.
In above image it is favorable to show Actual - Budget in Variance column for Revenue while showing Budget vs actual in Cosgs part.
Also Margin total should be negative for variance columns.
Adaxa has added Alow Opposite Sign flag on Report columns and Show Opposite Sign flag on report line. For any cell in report, when both flag are true then sign is reversed. After this enhancement report can be produced as expected value as below.