I see no reason to introduce a new wiring gauge standard just because the Americans have to be different from everyone else. If the present square millimetre standard is the most universal, then it is up to countries like the US to adopt it.
However, if the Americans want to be different and keep their wire standard, they can at least establish new names for their wires (based on the information in your chart) on the square millimetre designation.
The advantage to this for both the US and the world would be the ease at comparing sizes. Without a chart handy, one only can guess if a 2.50 mm² can be used in place of a #14 AWG. If the Americans renamed #14 AWG as 2.00 mm², then it is obvious that 2.50 mm² can be used in applicatons where 2.00 mm² is specified, but not the reverse.
Most of the Asian countries do not use the same sizes as the Europeans. The 1.25 mm² and 2.00 mm² you referance are two of the sizes used in Asia. The Asian sizes may have been based on the AWG standard, but long ago adopted to the square millimetre naming designation. In other words, they may be using the AWG sizes with a square millimetre designation. The two "standards" are easily comparable as a result.
All the Americans need do is investigate if the Asian sizes can safely be used in the US and if they can, it would be so easy just to adopt new names without changing anything or changing it ever so slightly.
The only reason the Americans won't do it is because of attitude. We are better then everyone else. They must change to our ways, not us to the theirs. The only reason for the resistance to adopting SI in the US is because the Americans are afraid the world would interpret the change as the US having been wrong for 200 years and gods are never wrong. So, everything is done the hard way. The US is only hurting itself.
