Open source refers to ProffieBoard. Warsabers appears to offer the CerbeRUS and ProffieBoard, so I think the first thing you should do is confirm what you actually have installed in your saber.
CerbeRUS appears to use plecter based files, atleast that is what the manual says, so if you have a CerbeRUS board that supports both plecter and smoothswing, then chances are you should get the CFX sound font.
However maybe its best for you to contact warsabers directly to confirm what they support