I understand this is more a ME problem, than an issue above all else.
Is there any way to make it so it uses the rando account 'SERVER' as the server tax account rather than an actual players account?

17.01 19:02:29 [Server] WARN Server economy account setting 'SERVER' doesn't seem to be the name of a known player! Please log in at least once in order for the server economy account to work.

This has nothing to do with this plugin but with ChestShop and its config itself. Your economy plugin would also need to allow fake players, there's nothing this plugin or ChestShop can do otherwise.

The only thing somewhat related that this plugin can do is log the admin shop (logging.admin-shop in the config)