I just tried it out on BHX-IST-SOF-IST-BHX (basically a return BHX-SOF)

This looks like it makes perfect sense
pretty much the same as a Q flight gives according to the Turkish website (2635 x2) 5270 miles


But when I tried this on Turkish...
OUTBOUND

INBOUND

This had both Q and H but both are 1635 again. So a total only showing 3270.

I'd LOVE to believe 12893 and it should be this (according to the tables they publish --- links in replies above)
But if I was constructing a mileage run to get status miles to take me over a threshold to retain Elite or move to Elite+ I would hardly be in a position to complain if I got the 3270 as its clearly what the booking page shows.

Having said that I really do like the tool you linked, thanks so much for that