I just tested Anslem with Observatory running.
I finished a YWC, with Anslem recovering with 15 recruits loaded. So Anslem is travelling with those recruits.
Scouting Post is active (and working).
I activated Observatory (Normal Star Chart).
Anslem land on Home Island, I load him with 165 recruits. I start a new YWC
and send my gens : first a vet, MaryXmas, 2 regulars and 2 BHG's (all skilled, differently but not all fully), then the champions Vargus, Nusala and Anslem. The "Send army" window shows a travel time of 4min 8sec :
But it didn't work as expected. Visiting the YWC adventure, it showed :
Others generals didn't seem to benefit from the Observatory buff either.