Is there a question here or just a rant? Does your application load when you have a reliable internet connection? Could it be related to your wireless carrier?
My solution for this possible situation is to create an offline functional application. In AGOL it's even easier to do than Portal because there are already offline enabled basemaps. In Portal you have to add these basemaps. Then the workflow for the crew is to change their settings to only sync while on wifi and to download an offline area of the map where they will be working. All the edit enabled feature classes have to be registered to the same database/datastore for the map to be enabled to go offline. Once the data is collected, we sync on wifi and reconcile and post. The last little nugget is you must enable the feature service to be edited by the data owner under the "features" section of the capabilities in Arc Server Manager. It is tedious, but full proof for working in offline or suspect network environments.
I'm sorry to hear that the beginning of the project was interrupted. If you believe you're running into a service performance issue that hasn't been posted to Status, it is recommended to contact Esri Support to report it. They can help quickly test/verify if something was going on with ArcGIS Online services.
ArcGIS Online, including hosted feature layers, are highly scalable, resilient and support a lot of important web-based GIS work each day, worldwide. That said, ArcGIS Online does not have an 100% uptime service commitment, nor is there a performance-based Service Level Agreement (SLA). The ArcGIS Online SLA details the service commitment ArcGIS Online does offer.
If your business case requires a higher/different SLA than ArcGIS Online can provide, it might be good to discuss some alternatives with your Account Manager.
I hope this helps,