Okay last note I promise because I think anon was just right all the way across!

I found a different service on opendata that uses the same names as the anon notes. But none of them are on SLRN.
So what might be happening is either the city's DLRN is being updated separately and that's what's feeding a separate data source for their base map on arcgis online, or their viewer is using non-city data (which I find unlikely but iunno). 
If I can load this other basemap they have into josm, I'll update it all.