Semitransparent equivalents

colors.css

// Compiled result

:root {
	--colour-soft1-0: #eadbea;
	--colour-soft1-25: #efe4ef;
	--colour-soft1-50: #f5edf5;
	--colour-soft1-75: #faf6fa;
	--colour-soft2-0: #ead2d5;
	--colour-soft2-25: #efdde0;
	--colour-soft2-50: #f5e9ea;
	--colour-soft2-75: #faf4f5;
}

colors.scss

$opacities: (
  0: 0%,
  25: 25%,
  50: 50%,
  75: 75%,
);

$colours: (
  soft1: #eadbea,
  soft2: #ead2d5
);

:root {
  @each $colkey, $colval in $colours {
    @each $opakey, $opaval in $opacities {
      --colour-#{$colkey}-#{$opakey}: mix(#ffffff, $colval, $opaval);
    }
  }
}