

Automatics also allow for engine braking. From a quick search, it sounds like a toss-up as to whether that triggers brake lights. Regardless, the article mentions the benefit is not only from cars slowing down, but also from indicating that a car is preparing to stop or “that a stationary vehicle might initiate movement”. Neither of those can be done by an engine brake, so front brake lights would still have a benefit even with a driver that likes engine braking.
That sounds like an issue with the underlying OpenStreetMap data that is used by Organic Maps (and CoMaps, and OsmAnd, and others). Map quality depends on where you are in the world and who is contributing to the maps there. If data is incomplete around you, you could contribute to it (but easier said than done, I know).
I can’t say why the route would be hours longer than Google maps, but I’ve noticed OsmAnd~ tends to overestimate drive time for me (I think it overestimates delay from traffic lights). Or it could just be that calculating routes on your phone doesn’t always give results as good as calculating routes on Google’s servers.