Hi not sure if it is a bug but I think it may be something worth looking at.

The spiders and the other mobs from the witch wood do leave the witch wood but do not leave the area however the pumpkin men do.

I ran into one in the feanwyyn weald which nearly killed me and would definitely kill most lowbies.

Perhaps make them not leave the ancient emerald forest like the spiders or even better make all the aggro witch wood mobs stay in the witch wood.

I also have seen the Jade Dragon in coastal plains do similar.