The effect of actual power imbalance per cylinder has no direct detrimental effect to crankshaft or bearing wear.

However the issue is AFR imbalance between cylinders caused by lack of individual cylinder trim ability.

Since I run weber mgmt on my car I have over come this by monitering individual cylinder EGT's and using injectors with normal variance in their flow rates to suit each cylinder.

That said my plenum has only 5% air flow variance from best to worst and this is also the kind of drift you can see in injector tolerancing so it's straight forward in balancing AFR's/EGT's by using a higher flow tolerance injector for the cylinders that flow most air.