Certainly in Australia this would be illegal as "deceptive and misleading conduct in trade or business"commerce" if your app was produced in the course of business. You are in trade or business and you are lying to another business that the add has been downloaded (true) and read (false).
From the ACCC:
It is illegal for a business to engage in conduct that misleads or deceives or is likely to mislead or deceive consumers or other businesses. This law applies even if you did not intend to mislead or deceive anyone or no one has suffered any loss or damage as a result of your conduct.
Many people think this only applies to advertising and promotion, this is not true, it applies to all conduct of the business.