I have updated the model to better account for recoveries. I actually now use two different approximations to form a delay differential equation. While there remains some amount of hand-waving in the justifications, the results seem to be in accordance with current data for many of the locales I checked. Also some of the miss-prediction might be from increases in testing rather than underlying changes in the disease spread dynamics.
Since the notebook contains a lot of graphics and is therefor on the longish side I am attaching it rather than as a Wolfram Cloud notebook.
Edit: It seems the notebook is not appearing. Not sure why but I will make inquiries, as they say.
Edit 2: It was added though not by me. I need to get a magic touch upgrade or something.
Edit 3: I was informed that the attachment is difficult for some to download (maybe a size limitation on some computers?), so I have now posted directly as a Cloud-based notebook.