Hi, This is a known problem but has not easy solution:
XFrog plants are composed by several grouped objects. Since Forest requires a single mesh, these objects are attached together in the importing process. Once loaded, there is not reference of the previous pivot point.
This should be the procedure to fix these items:
1) Unhide and unfreeze the forest_templates layer (imported objects are stored here).
2) With the Forest object selected, use right click->Select Forest Custom Object (quad menu), to select the plant you want to modify.
3) Once selected, apply Group->Explode from the Max menu.
4) Align the pivot point correctly. Forest items will be updated automatically.
5) Freeze and hide the forest_templates layer.
Anyway, for next updates we'll check if we can implement an easier workaround. For example, that Geometry->Offset modifies the pivot point.