Average of 3-color tuples

mix.js

const hexs = [
  // Karjala
  [ '538854', 'be2928', '000000' ],
    // Ludic
  [ '529f54', 'be2928', '3d3b7b' ],
  // Veps
  [ '16b370', 'ffff00', '155cdc' ],
  // Russian-side Finnish
  [ 'ffd301', 'ef2d20', '0167b3' ],
  // Izhorian
  [ '000080', 'fed801', 'd70000' ],
  // Votic
  [ 'ffffff', '0099ff', 'ff0000' ],
  // Siberian-Estonian
  [ 'ffffff', 'ee0013', '150068' ]
]

const parseHex = flip(parseInt)(16)

const toHex = invoker(1, 'toString')(16)

const average = converge(
  divide,
  [
    reduce(useWith(add, [identity, parseHex]), 0),
    length
  ]
)

const mix = compose(
  map(compose(toHex, Math.round, average)),
  transpose
)

mix(hexs) // => ["88ab3a", "c39013", "5224a3"]

1: Original output
2. Manually corrected