Hello Jim!
Thanks for sending us your Cubase project. I hope you don't mind that I fill in for Paul here.
The sfz, sffz patches only have one dynamic layer. So there are no velocities that can be crossfaded. The only effect you get is a slight change in volume. This effect is also there in the Dimension Cellos, but I agree that it is less audible in your example than with the Dimension Violins. Anyway, it might be more useful to automate the Expression or Volume fader in your case. This way volume changes will be more audible.
The dyn-me_2s patches have two velocity layers. So a velocity X-Fade should have an audible effect.
Another possibility would be to make a Slot X-Fade between the sffz and dyn-me patches. That will probably the best solution for your example. For this you will have to add the dyn-me patches to the b-slots of the sffz cell first and activate Slot X-Fade.
Best regards,
Andi