I can’t tell anything about the plug in development, but I try here to get some data, so the problem is solved faster, if possible. Perhaps PLA needs to be checked on, to get all the needed information into the FBX for Unity.
Just from an image, hard to tell. If you can share the scene file, that would be more helpful.
I just went from Cinema 4d via CV Smart Export to FBX, then merged this FBX into a new scene file to check the quality of the export, and then opened it in Unity. Of course no particles nor attractors, too many ways to employ them.
Perhaps this little test delivers already some usable hints for the next step.
All the best