where did you get the idea that TSL robes are "formal robes", and the Kotor robes the council wore on dantooine were "informal"? i'm not so sure about that, i've never heard of "cerimonial robes" and general purpose robes. on Rakata Prime some council members wore the robes you see on Zez and Vash, those too have never existed.
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Yes they are informal looking, they dont look like Jedi robes, now what sort of colours are orange and blue for a jedi robe " I'm pretty sure the K2 robes look more jedi like and better/realistic