Depending on the language project and the editor community guidelines, bad revisions can live for a various amount of time. If you are using the Realtime API, when the community handles this inaccuracy it will update you with the new page content automatically in a new revision event. If you are not using the Realtime API, you can hit the On-demand API and query the specific page to get the most up to date version of the page and replace it. Keep in mind, the On-demand API will only reflect what is live on the projects.
As a tip, we encourage you to use the scores field to assess new revisions for potential vandalism. There are two machine learning based models included, one predicting whether a revision is damaging and another predicting if the revision was made in good faith - see our documentation for more information. In the future, we are working to provide more data to help you determine validity. Keep your eye out for an announcement when that’s ready.