You absolutely need some further editing (tweaking?) after having applied film negative. But the amount of editing needed is much less compared to the situation when you use the basic RT tools only?
I suppose that the film negative tool is the first you would apply working on a negative. Where is film negative placed in the pipeline (I assume it is placed very early) and is it designed to be applied only once without the need for adjustments later on? A later adjustment of the film negative settings will surely cause a need to readjust other tools placed later on in the pipeline.