Probably out of context in this discussion and not possible or very difficult to apply, but really short ‘round-trip times (RTT’s)’/latencies are of course not possible from every part of the world. Maybe there is a way to use that.
If you can ping from ‘source’ devices from different parts of the world to the same target, there should be some who give shorter RTT’s than others. If the RTT is e.g. never lower than a certain value (from any source), you could reject the target. And if there are RTT’s short enough that it has to be in the ‘neighborhood’ of the source device(s) who pinged, you have an rough idea where the target is located. Do that for all 12 targets and check if they are not all in the same ‘neighborhood’.