re: Walna Scar Road loop
Just near the western edge of the FC woods on Broughton Moor, I'd be tempted to head up the fireroad (north) until just out of the woods, and then head back down the b.way just the other side of the stream back down to Stephenson Ground. It'd make for a good descent for a straightforward climb
You could extend it by heading SW at stephenson ground toward stainton ground, and theres a few more b.way options round there
Once you get to just south of Little Arrow Moor, (just past the 'walled in' rocky 90deg turns)
I prefer* to cut across to the b.way that follows the stream and then a walled track into Torver as theres more rocky offroad than heading into coniston itself on wide smooth tracks and a road
*I've not ridden the b.way down to Spoon Hall though
re: the langdales
On descending toward Elterwater I much prefer the other b.way descent (that heads N) than the NErly one you've got highlighted. Much tighter and techy
Also the b.way above Clappergate going toward Loughtrigg Tarn was good last time I rode it (though I'm not 100% sure they haven't 'improved' it since October), should be much better than the road anyway