This is the problem. When you are in era 4, this file should be named "global_layer.csv" and the other ones "1943_global_layer.csv", "bob_global_layer.csv"...
When you run the era swapper, be sure that all folders are closed and no file is open otherwise, there is a risk that a file or a folder is not renamed.
To correct this, you have to rename files in global layer folder manually.