You can try getting the latest version from the developer's the download page scan that. You can also request a manual review to determine the current status of the app on Rosetta 2.
Currently, Rosetta 2 is a proprietary Apple software that is only available on macOS on Apple Silicon devices. This means there isn't any way to test Rosetta 2 compatibility with an app without a physical Apple Silicon device and so you definitely can't test that with just a website alone... for now... Feel free to signup for email updates.
Most apps will work with Rosetta 2 translation well but it's not a perfect technology. Some apps will have various small issues and graphical bugs but will work well enough, a few apps will fail to launch entirely and some apps will runs with virtually no issues and perform even faster than an equivalent Intel-based Mac. For now the best way to determine how well an app will run under Rosetta 2 is by human review.