Hi,
This is exactly where pathfinding frameworks fails to deliver a suitable api... so...
The way to go about it would be set up a trigger around the destination, so that when an agent trigger that volume, you know he's close enough and you can then set him to the next destination.
that would be the more sensible and 100% reliable system. Now it could be problematic if several agents are trying to access the same way point, but that would be already something to adress specifically for your needs.
I am not sure I can propose another solution that would be as reliable.
Don't hesitate to report back this via the unity bug reporting, I did, the more they hear about this, the better, they might address it properly in a future update.
bye,
Jean