The affix vuñ comes after the words kaccha etc. in the senses of born etc. when the meaning is 'a man' or 'what exists in a man'.,
This debars अण् ॥ Thus काच्छकः 'a man born in Kutch', काच्छकमस्य हसितं जल्पितम् ॥ 'His joke or talk is of Kutch or a Kutch-laughter'. काच्छिका चूडा ॥ Similarly सैन्धवको मनुष्यः, सैन्धवकमस्य हसितं जल्पितम्, सैन्धविका चूडा ॥
Why do we say \when meaning man or what exists in man?\ Observe कान्छो गौः 'The cow of Kutch'. सैन्धवो वार्णवः ॥,