The Parameter Optimization node works as expected - thanks! The additional feature I miss is possibility to change from "linear" search to another option (eg 10^parameter). I think it could be easily implemented. The default would be linear search, but user could enter an expression he want to get on the output flow variables (like 10^parameter).
Another feature, which would be probably more difficult to implement, is "extensible" parameter range. So if search strategy is Hillclimbing and the function still raises, the search grid can be extended.
(both features are similar to Weka's Grid Search, which is unfortunatelly limited to Weka's nodes).