AFAICS it's quite trivial implementation at the moment, and would otherwise require parsing the text file to find some references, right?

Yes, but the main issue is the parsing, it needs to have a specific standard. We use HOCON because it is great to read and edit (basically JSON would be a subset of HOCON)

the original pyhocon does support include statements as you mentioned -

Correct, my thinking was to expand them into "@configuration_section.key" or something of that nature