he proly used a mod for normal sins or the mod he had did not contain the entity.manufest (it least thats what it sounds like)

In the Entrenchment folder. If you mod an entity file for example you need to copy the entity.manifest file to the mod directory and edit it so the entity count is higher and add the new entity to the list.

exactly. the entity.manifest is a list of all files entrenchment should load. just add any new files to it. keep in mind some files for entrenchment are already there. and you still got to add files that you have taken from original sins (if entrenchment does not have those files in its gameinfo folder).

if you want any files in the game info folder read, it has to be listed in the Entity.manifest. anything not listed in that manifest will be ignored by the game.