That's it - I'm dry. I added Hinterworlds routes from Challenge #39. Note that if you look at the maps in that resource, you'll find there are two distinct sets of routes - the large "trade runs" that span the sector shown on the full sector map, and smaller communication (?) routes in the subsector maps. I went with the communication ... but I'm still pondering the decision.
(As an aside: the sector map is really poorly put together, which is surprising given who worked on it and who published it. I'll write that off to a bad month.)
I (hopefully) have Travellers' Digest #10 and #18 inbound, which means bits of Core and all of Corridor and Ealiyasiyw's routes should be in soon - assuming my favorite source is correct.
So what's next?
I'm thinking I'll spin up a quick web service and have the page ping it when you scroll (after a short delay, of course). It'll pull the credits for whatever is centered - subsector names, world data, route data, dates, etc - and display it as an overlay in the corner of a map.