The problem is that Aric's mod was never designed to use the Old Emily images. In expansion.gd, there is a dictionary containing the body images of each of the unique characters. That dictionary uses the file paths rather than gallery.gd to access the images, thus is not affected by Constants. The simplest way to change this is to add "old" to the start of each of those file names, so changing 'res://files/images/emily/emily2happy.png' to 'res://files/images/emily/oldemily2happy.png'.