Appears to only work for some planes:
I tested with F15 and it landed then crew got out and after few mins despawned , and plane stayed on the ground and never did any further waypoints.
I then tested again changing plane to an KC130 and it landed refuelled and flew next 2 waypoints and landed at another airport.
So it worked for the KC130 but not the F15. So I'm guessing this AI script only works for fuel tanker planes like the KC130. (or its broken for some planes)
You also prob need to set the refuel time long enough but not too long (if guys that get out of plane despawn I think it also may fail to work)
Also the bingo fuel makes don't seem to matter.
Its quite finicky and buggy IMHO, I got some very odd behaviours during testing. (like not wanting landing as specific airports , even flying back to original refuelling airport to land even when told another one, it turned around and flew back in one scenario)
I only used 5 % initial fuel during testing, so I'm sure it did refuel
(AI does some retarded things that just take experience to find and work around. It was same when I made missions for IL-2 GB, the fun of mission building....