InDesign Scripting -> Profile-based color conversions?

If you change the document’s assigned CMYK profile you will get different color managed Lab values by simply changing the color’s space property.

Something like this, where I’m making a new swatch, setting the document’s profile assignment, duping the swatch, get the dup‘s Lab values for the provided CMYK profile, and removing the dup.

var docprof = app.activeDocument.cmykProfile;

var profA = "U.S. Web Coated (SWOP) v2";
var profB = "U.S. Sheetfed Coated v2";

//Create a CMYK color.
try{
    var mycolor = app.activeDocument.colors.add({name:"Red", model:ColorModel.process, colorValue:[20, 100, 100, 0]});
}
	catch (e){
    var mycolor = app.activeDocument.colors.item("Red");
};



/**
    *Get a swatch’s Lab Value
    * @param s the swatch
    * @param p the CMYK Profile
**/	
function getLAB(s, p){
    app.activeDocument.cmykProfile = p;
    var d = s.duplicate();
    d.space = ColorSpace.LAB;
    val = d.colorValue;
    d.remove();
    return val;
}

var lab1 = getLAB(mycolor, profA);
var lab2 = getLAB(mycolor, profB);
$.writeln("SWOP: " + lab1 + "\nSheetfed: " + lab2)
//returns   SWOP: 44.9591979980469,62.1322975158691,40.0155982971191
//          Sheetfed: 41.3518981933594,56.3812980651855,43.5097007751465

//reset profile
app.activeDocument.cmykProfile = docprof;

If you know some AppleScript you might look at this branding script I wrote that makes a color managed swatch book from Lab spot colors. The link includes the Applescript with annotations

https://community.adobe.com/t5/indesign/branding-color-guide/td-p/10818696?page=1