The only thing you can do is to create another project in Mendix 7.23.0, import excel exporter template magaer to this project, export the module again and import this exported module to your 8.4.2 project.
Unfortunately this is the upgrade path you need to take. Since this is a version that is released for Mendix 7, there is no guarantee that it will work on 8.x but you can give it a try.
You could do a test project ion the described version and then manualy export the module from the test app to the newer app. Its not nice, but it should work. The module will then be displayed as a regular module and not on the app store module area (blue marked modules)