Yeah sorry please see below
CAI-xMAD-xDOH-DPS-xKUL-TYO-CTS-xHKG-PER-SYD-DFW-SEA-xDFW-SCL,GRU-DOH
I can say for sure that the system would allow MAD as as stopover if needed. I tried SCL-LHR-CAI with and without it as a stopover and wouldn't work. I tried various options for a stopover in Europe on return and would not allow it kept saying I could only have 2 stopovers in origin region even when I had no stopovers in Europe middle east.
I also couldn't get it to allow the final sector of DOH-CAI so left it as open jaw. Easy enough to pay final flight there if there's still good options out of CAi next year.
I also tried SEA-DFW-SCL in various combinations and it failed but when I put in SEA-SCL it allowed it. Might be me but I couldn't see anything wrong with it.
I also tried to have ANC in my itin but everything I tried failed I could get there but always told me the return was more than 2 sectors with ANC in it. Made no sense but I gave up.
The other transit points on my itn I did not try as stopovers as did not need to stop but I suspect they would have been OK.
Hope that helps