Last time I went looking for this it took weeks of hacking. This time around I got in pretty quickly. Looking at the item description, I have a theory about the trigger. The key bit is:
This database seems to be a study on the same language you saw on the ancient document you intercepted heading to Midgard.
I think my mistake last time might have been to use ancient notes and the yellowing map I had lying around in my inventory from previous runs without having actually rerouted the shipment and seeing that it was intended for Midgard in my current run. So, I suspect the non-painful way to do this would be to first reroute both the notes and map (only one or the other might be necessary), saving level 6 sites for later. Then use both the notes and the map. (Dunno if only one is necessary or, if both are necessary, whether order matters.) Then, and only then, start looking at level 6 sites for the mysteriously language database.