Many thanks all of you for the replies and directions.
I could accomplish my palette building and further by using:

Adobe Color: https://color.adobe.com/create/color-wheel
SE-ColorMaker (Desktop application): http://se-soft.com/lang/en/
Paletton - The Color Scheme Designer: http://paletton.com/
COLOURlovers Palettes: https://www.colourlovers.com/palettes

The following content about color theory was quite instructive:
https://worqx.com/color/color_basics.htm

Also, the table above and the older Xara thread about Colours pointed by Jonopen was of imediate usage:
https://www.talkgraphics.com/showthr...?35124-Colours

Regarding Adobe Color, on the bottom left it is possible to choose the HSV color mode also used by XDP:
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The palettes from Adobe Color can be exported as .JPEG or .ASE (Adobe Swatch Exchange).
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I realized XDP can't import .ASE file directly.
=> By chance does anyone know a workaround to import .ASE into XDP without having to use Adobe software as intermediate (e.g. Photoshop opening .ASE, then saving as .ACO)?

Cheers,
Carlos