Hi @Anonymous,
Do you want to add your MS Planner connector as data source within the Edit form?
Based on the issue that you mentioned, I think you have some misunderstanding with Edit form and Data source types in PowerApps.
Currently, within PowerApps, the DataSource property of the Edit form control is required to provide a tabular data source (e.g. SQL Server, SP list, Excel table, etc), but the MS Planner connector is a Action data source.
More details about the date source types in PowerApps, please check the following article:
Data Source types
If you want to add your MS Planner connector as data source within the Edit form or edit your MS Planner Tasks in Edit form, I afraid that there is no way to achieve your needs in PowerApps currently.
If you would like this feature to be added in PowerApps, please submit an idea to PowerApps Ideas Forum:
https://powerusers.microsoft.com/t5/PowerApps-Ideas/idb-p/PowerAppsIdeas
Best regards,
Kris