Although you have followed the documentation to provide a Spanish translation to your users, some of them reported that the app still appears in the English version. What might be the reason behind that?
Here is a snapshot from the res directory tree:
res/
├── values/ # Default resources for Values
│ ├── strings.xml # Strings in English
│ └── ...
├── values-es/ # Values Resources for the Spanish language qualifier
│ ├── strings.xml # Strings in Spanish
│ └── ...
└── ...