Hi Adelaide,
I can see the same error you mentioned when clicking Edit in Survey123 Connect from AGOL org survey form options. This could be a protential issue we need to address. Could you contact your Technical Support to log this issue so that you have a record to follow up the issue status? By logging a salesforce issue would also help Survey123 team to track how many users are impacted by this issue and would promote the priority of the issue fix for our furture release.
To workaround this and open the survey in Survey123 Connect, you can sign in your portal in Connect:
Use Survey123 with ArcGIS Enterprise—Survey123 for ArcGIS | ArcGIS
After signing in, you should be able to see the survey from the menu and move on.
In addition, I saw that you had aceess to the surveys which were created on survey123 website and never published and transferred to you. Currently, there is no possible method to grant the permission to other users to edit the design of the survey except the owner of the survey.
If you would like to modify the survey which are shared with you but owned by others, you will have to copy the survey form and re-create them.