It would appear that other players have experienced similar error messages with other mods.
https://forums.civfanatics.com/threads/gfc-error-failed-to-initalize-primary-control-theme.509184/
https://forums.civfanatics.com/thre...-initialize-the-primary-control-theme.251332/
https://forums.civfanatics.com/thre...he-primary-control-theme.265892/#post-6564074
Looks like it is purely down to where in your directory you have the Mod installed
https://forums.civfanatics.com/threads/gfc-error-failed-to-initalize-primary-control-theme.509184/
https://forums.civfanatics.com/thre...-initialize-the-primary-control-theme.251332/
https://forums.civfanatics.com/thre...he-primary-control-theme.265892/#post-6564074
Looks like it is purely down to where in your directory you have the Mod installed