Best way to create color palette in sass with opacity values or translate opaque colors to base colors

I am restructuring the whole sass setup for a client, and for the purpose of their color palette I have created a map with contains the palette. For the sake of the client I have inserted some fake color values in this question.

$foundation-palette: (
    primary: (
        blue: (
            base: rgba(155, 177, 255, 1),
            light: rgba(155, 177, 255, 75%),
            lighter: rgba(155, 177, 255, 50%),
            lightere: rgba(155, 177, 255, 25%),
            lightest: rgba(155, 177, 255, 15%),
        ),
        beige: (
            base: rgba(255, 233, 155, 1),
            light: rgba(255, 233, 155, 75%),
            lighter: rgba(255, 233, 155, 50%),
            lightere: rgba(255, 233, 155, 25%),
            lightest: rgba(255, 233, 155, 15%),
        ),
    ),
    secondary: (
        base: rgba(233, 151, 144, 1),
        light: rgba(233, 151, 144, 80%),
    ),
    tertiary: (
        green: (
            base: rgba(109, 192, 102, 1),
            light: rgba(109, 192, 102, 75%),
            lighter: rgba(109, 192, 102, 50%),
            lightere: rgba(109, 192, 102, 25%),
            lightest: rgba(109, 192, 102, 15%),
        ),
        ....
    ),
    white: #fff
);

The issue is, that the color palette contains a number of colors which all have different shades defined with an opacity value.

With the current setup, the opacity values doesn't get registered, meaning that when I try to use the primary-blue-lightest color it will just be compiled into the base color of that (no opacity value).

However, I am wandering if I should even declare the color palette with opacity values. Even though it is in the design principles of the client, I wonder how good a practice this is in your sass setup. For example if I want a light grey color, it would be an opaque version of black.

Depending on this I either want to declare the colors without opacity, But how do I find the correct color value of the rgb value with will match with the opaque version?

If it is fine to use opacity in your color palette, I am wandering why the 'lightest' value for example compiles into the base color. What is the guideline here ? and how should I go about this ?

Any input is appreciated

EDIT: I am accessing the colors by doing a map-get:

$primary-blue-lightest: map-get(map-get(map-get($foundation-palette, primary), blue), lightest);

Solution

Another simple approach could be to create a function and pass the base color and the opacity as argument:

@function colorPalette($RGBColor, $opacityLevel) {
  @return rgba($RGBColor, $opacityLevel);
}

Then you can create a variable off of this function:

$green: colorPalette(rgb(0,255,0), .9);

And use it:

.section { background-color: $green; }