I am bit perplexed about this hangup about whether one is limited to 10kt or 15kt tailwind.
Notwithstanding what a particular operator might decree in their instructions to crews, surely this is purely a landing performance issue assuming the flight manual data is available up to 15 kts tailwind and 10kts is not shown in the AFM as a hard limitation?
When I was on the B737-200 some years ago the operator I flew for had 15kts tailwind data for all airports we operated to, both for take off and landing.