Karabiner config: Left CMD → EN, right CMD → RU

cmd-lang.json

{
  "title": "Non-modal input language change",
  "rules": [
    {
      "description": "Switch to RU",
      "manipulators": [
        {
          "conditions": [
            {
              "input_sources": [
                {
                  "language": "en"
                }
              ],
              "type": "input_source_if"
            }
          ],
          "from": {
            "key_code": "right_command"
          },
          "to_if_alone": [
            {
              "select_input_source": {
                "language": "ru"
              }
            }
          ],
          "type": "basic"
        }
      ]
    },
    {
      "description": "Switch to EN",
      "manipulators": [
        {
          "conditions": [
            {
              "input_sources": [
                {
                  "language": "ru"
                }
              ],
              "type": "input_source_if"
            }
          ],
          "from": {
            "key_code": "left_command"
          },
          "to_if_alone": [
            {
              "select_input_source": {
                "language": "en"
              }
            }
          ],
          "type": "basic"
        }
      ]
    }
  ]
}