I've cleaned up my original post, as the correct implementation of the 6.0a template corrected the notehead and roll issues I was experiencing.
I am still wondering if something can be done with regard to severe re-articulation after tied and/or slurred sustains (e.g. concert BD rolls, mallet rolls, etc.). I am using the cresc/dim playback plug-in as suggested in another post in order to accurately render sustained sounds during those expressions, but the re-articulation still occurs at the next note value—regardless of whether I change the dynamics during the sustain.
What I am doing to compensate for now is adjusting the plug-in so that the crescendo (or decresc.) goes to the next dynamic above the following note—so that the re-articulation is not heard as much. However, for sustained sounds without dynamic expression, is there anything I can do to prevent this? It seems that the volume of the sustained sounds may be reduced, so is that what's causing this?