ShiftLanguages.json

{
  "title": "Language toggler",
  "rules": [
    {
      "description": "Language toggler on SHIFTS",
      "manipulators": [
        {
         "conditions": [
            {
              "type": "input_source_if",
              "input_sources": [
                {
                  "input_source_id": "com.apple.keylayout.Australian"
                }
              ]
            }
          ],
          "type": "basic",
          "from": {
            "key_code": "left_shift"
          },
          "to": [
              {
                  "key_code": "left_shift",
                  "lazy": true
              }
          ],
          "to_if_alone": [
            {
              "select_input_source": {
                "input_source_id": "com.apple.keylayout.RussianWin"
              }
            }
          ]
        },
        {
         "conditions": [
            {
              "type": "input_source_if",
              "input_sources": [
                {
                  "input_source_id": "com.apple.keylayout.RussianWin"
                }
              ]
            }
          ],
          "type": "basic",
          "from": {
            "key_code": "right_shift"
          },
          "to": [
              {
                  "key_code": "right_shift",
                  "lazy": true
              }
          ],
          "to_if_alone": [
            {
              "select_input_source": {
                "input_source_id": "com.apple.keylayout.Australian"
              }
            }
          ]
        }
      ]
    }
  ]
}