You're right. The collapse of Coolsteph Island should have made the Boomsticks go extinct, but they aren't marked as such. They must have gotten to Ramul Island without updating the species page. It is an oversight that there's not even a Coolsteph Rock(s) to represent tiny, low-lying islands around Drake that might allow island-hopping.
While tracing this submission's ancestry, I realized the image for the Cryocanon is missing.
How tiny are its seeds? Do they have special adaptations to being picked up my wind, or are they just very light and small? According to some cursory research, orchid seeds are typically the size of a speck of dust, so it getting into the atmosphere via explosive force and wind is pretty plausible.