Okay, that's a very complete question now.
I don't use Harvest, but from time to time get involved in troubleshooting. You could feedback on Github (maybe offer that general feedback on the docs and also the particular first step where it doesn't work).
For example, if your collector works, but data isn't making it to the DB, then DB logs or Prometheus scraper logs, perhaps. If E-Series data is making it to the DB but Grafana doesn't work, I'd go to Grafana "free query" or "explore" area and see if I can find any E-Series metrics (if yes, then the issue is the dashboards, if no, but other metrics work, then maybe it's the DB tables). If even collection of raw data from E-Series doesn't work, then provide collector logs and someone will look into that.
If you don't care about which specific tool you use, you could just use the collector (poller) and the rest can be your own infra (scrape Prometheus metrics and insert in own DB, create own dashboards). Or even use another E-Series collector from Github.
