Sorry for bringing this up very late, but my Fantasea LED trigger does fire my Sea and Sea YS-D2J's however wouldn't work with any of the shop bought standard fibre optic cables for UWP.
I ended up using flexible 3.5mm side glow fibre cable, encased in a black hose and wrap it close to my strobe arms, there is more than enough light produced to light the sensors in the YS-D2j's... If you don't wrap the FO cables in black hosing then bright sunlight can trigger the strobes by hitting the FO cables.
My problem is I have made one pair of these cables but when I reordered the cable to create spare cables I get a different ones, either non-flexible or with an external skin making it too wide. To make they cost around £10 ($13) to make 2 including connectors at each end, no skills needed other than to be able to measure and use a sharp knife.
As said the LED's put out enough light the problem is the amount transmitted by the commercial FO cables.