Prevent Google play from auto translating my app description
From this link:
https://support.google.com/googleplay/android-developer/answer/3125566?hl=en
There is a section Add translations for Store Listing pages which covers your question.
The specific quote on how Google Play treats translations of Store Listings:
After you publish an app on Google Play, automated translations of your app's Store Listing page are available to Google Play users.
If users visit your app's Store Listing on Google Play in a language that you haven't translated, they can choose to view an automated translation of your app's page. Near the top of the page, there will be a notification that explains the translation has been done automatically, along with an option to view the Store Listing in its default language instead.
So if you don't provide a specific language translation, Google gives the choice to the user of seeing a automatic translation.