Quick update on this: echo devices can't be enumerated any more because the api isn't being initialized. This could be the reason why restoring from backup works, but anybody who wants to set up Echo Speaks from scratch is out of luck. Since this app (and my app) both used a somewhat sketchy developer api, I'm not surprised that Amazon changed or disabled the functionality. I'm actually surprised that it ran for as long as it did. I've therefore decided to switch over to Airplay for my HE TTS needs. This works well with Hubitat's Airplay integration app and my homepod mini devices.