I believe that none of the marks (
sfz, sffz, fp, etc.) that are more complex than just a strict signpost for a specific key velocity (
pp, mf, fff, etc.) are wired for playback. To approximate some of the effects you are looking for, use regular dynamics and hide them from view so that only the non-wired expression is shown. It isn't always possible to create realistic dynamic changes like
fp, so let's hope that all these markings will make it to the playback world soon... Alternatively, you could shop around for a VST sound set that includes the effect you are looking for and run it as an adjunct to the Notion sounds. Or you could start lobbying for such an expansion of Notion's sound set, if you have lots of energy and persistence.
Best wishes,
Thorrild