OK, but do you think the bridleway could start with this one instead?
https://www.openstreetmap.org/way/24395429
I see a sign on Mapillary but it’s impossible to read it: https://www.mapillary.com/app/?pKey=357925339508176

So, perhaps a L-shape bridleway to Belle-Alliance and the northmost part is only a footway.  That would make sense but I cannot confirm it.