Same here. Up to a few millions of documents, this is already great. Combine this with a few other simple techniques and extra metadata during ingestion, and you already have a system that practically useable.

I have tried this by ingesting all of cloudflare's highly technical complex documents (more than 3000 A4 sized pages) and then comparing results with that of cloudflare's own chatbot in their dashboard.

In all cases my system either matched, or performed marginally better than cloudflare's own bot.

I do use a few more techniques though, but, not RDF triplets, and definitely no custom trained neural network.