Regarding manual or tutorial, I agree that its difficult to manage the fields. I namespace the fields into profile, income statement, balance sheet and quotes so ideally you only have to search [incomeStatement...] and see some fields. But I'll try to list them all out.
Regarding the enums, I thought about that before and wanted to implement auto-complete enums in the language grammar but so it was bit complicated so I decided to kick the can, but I'll circle back around to it. There are only a few string fields and I put in regex matching so you can just do contains `contains "electric"`
What queries didn't return? It's a static site, it shouldn't be affected by the traffic.
The historical data is tough because reporting periods aren't all the same. I don't have a back tester either. I did have a feature before where you can plot any attribute historically, but I didn't find it that useful.