// Array1
[
 0: [ ID: 0, translationcode: 'a' ],
 1: [ ID: 1, translationcode: 'a' ],
 2: [ ID: 2, translationcode: 'b' ],
 3: [ ID: 3, translationcode: 'c' ]
]

// Array2
[
 0: [
      0: [ ID: 0, translationcode: 'a' ],
      1: [ ID: 1, translationcode: 'a' ]
    ],
 1: [ ID: 2, translationcode: 'b' ],
 2: [ ID: 3, translationcode: 'c' ]
]

let found = arr2.some(function (el) {
      return el.translationcode === item.translationcode;
 });