you need change imports in buffer file .py
change this :
import sys
from net.sf.l2j.gameserver.model.actor.instance import L2PcInstance
from java.util import Iterator
from net.sf.l2j.gameserver.datatables import SkillTable
from net.sf.l2j import L2DatabaseFactory
from net.sf.l2j.gameserver.model.quest import State
from net.sf.l2j.gameserver.model.quest import QuestState
from net.sf.l2j.gameserver.model.quest.jython import QuestJython as JQuest
for this :
import sys
from com.l2jserver.gameserver.model.actor.instance import L2PcInstance
from java.util import Iterator
from com.l2jserver.gameserver.datatables import SkillTable
from com.l2jserver import L2DatabaseFactory
from com.l2jserver.gameserver.model.quest import State
from com.l2jserver.gameserver.model.quest import QuestState
from com.l2jserver.gameserver.model.quest.jython import QuestJython as JQuest
restart server and must work, next time use code or quote for a long list .