Modding Graphics
From UnReal World Wiki
Graphics
How to make it visible Unreal world uses a system where all created objects in a savegame have their own attributes, therefore it is possible to craft an item, modify that item in the mod and the already crafted item will retain its former stats.
Because of this, it can appear as the graphic you gave an object didn't update. That's because it didn't. The old item doesn't know that it should use the newly defined TILEGFX command.
Solve this by crafting a new instance of the object. For testing graphics it is therefore suggested that a free version of the item being tested is made, so it can easily be produced again and again.