But you're not describing a square with the cross at 20% down from the top, that's a Diamond.
We just built a couple using this plan
by Charlie Charlton, equal spreader and spine lengths at 100 cm with the spreader at 15% which puts the profile more in the realm of the Malay then an Eddy, but if the sail is tight and not baggy it's not an Eddy or Malay, it's a Diamond. And that's what we call ours, well we actually call them 'Teagan' because the appliqué is of our granddaughter but classify them as "Diamonds".
Although our kites don't need them we built bow tie tails for them because Diamonds just need a traditional tail like we made from Moms old sheets as kids. Without the tails they really dart about following our swirling winds but fly fine.