The latest documentation for plugin.xml specifies an example target of "res/values/FooPluginStrings.xml" ( https://cordova.apache.org/docs/en/latest/plugin_ref/spec.html#resource-file ) however this location causes errors as it implies the older project style as in those created pre cordova-android 7. Builds then fail.
Specifically the presence of a res directory causes cordova-android to assume an eclipse / non android studio project in [cordova-android/framework/src/org/apache/cordova/]AndroidStudio.js:26 which in turn causes cordova to look for the [root]/AndroidManifest.xml via [cordova-android/framework/src/org/apache/cordova/]AndroidProject.js:96. However since cordova-android now no longer creates the [root]/AndroidManifest.xml file builds fail.
I do not know where the new location should be. Poking arround android studio my best guess for this example would be "app/src/main/res/values/FooPluginStrings.xml" however I am unsure if this is actually correct.