karabiner-elements: perfect solution while changing language inputs between EN and ZH (Location: ${HOME}/.config/karabiner/assets/complex_modifications/)

remapLRShift.json

{
  "title": "LR_Shift to Ctrl+Space",
  "rules": [
    {
      "description": "Change L_Shift to switch EN/ZH condition",
      "manipulators": [
        {
          "type": "basic",
          "conditions": [
            {
              "input_sources": [
                {
                  "input_source_id": "^com\\.apple\\.keylayout\\.ABC$",
                  "language": "en*"
                }
              ],
              "type": "input_source_unless"
            }
          ],
          "from": {
            "key_code": "left_shift",
            "modifiers": {
              "optional": ["any"]
            }
          },
          "parameters": {
            "basic.to_if_alone_timeout_milliseconds": 333,
            "basic.to_if_held_down_threshold_milliseconds": 333
          },
          "to": [
            {
              "key_code": "left_shift",
              "lazy": true
            }
          ],
          "to_if_held_down": [
            {
              "key_code": "left_shift"
            }
          ],
          "to_if_alone": [
            {
              "select_input_source": {
                "input_source_id": "^com\\.apple\\.keylayout\\.ABC$",
                "language": "en*"
              }
            }
          ]
        },
        {
          "type": "basic",
          "conditions": [
            {
              "input_sources": [
                {
                  "input_source_id": "^com\\.boshiamy\\.inputmethod\\.BoshiamyIMK$",
                  "language": "zh*"
                }
              ],
              "type": "input_source_unless"
            }
          ],
          "from": {
            "key_code": "left_shift",
            "modifiers": {
              "optional": ["any"]
            }
          },
          "parameters": {
            "basic.to_if_alone_timeout_milliseconds": 333,
            "basic.to_if_held_down_threshold_milliseconds": 333
          },
          "to": [
            {
              "key_code": "left_shift",
              "lazy": true
            }
          ],
          "to_if_held_down": [
            {
              "key_code": "left_shift"
            }
          ],
          "to_if_alone": [
            {
              "key_code": "spacebar",
              "modifiers": ["left_control", "left_option"],
              "hold_down_milliseconds": 1
            }
          ]
        }
      ]
    },
    {
      "description": "Change R_Shift to switch EN/ZH condition",
      "manipulators": [
        {
          "type": "basic",
          "conditions": [
            {
              "input_sources": [
                {
                  "input_source_id": "^com\\.apple\\.keylayout\\.ABC$",
                  "language": "en*"
                }
              ],
              "type": "input_source_unless"
            }
          ],
          "from": {
            "key_code": "right_shift",
            "modifiers": {
              "optional": ["any"]
            }
          },
          "parameters": {
            "basic.to_if_alone_timeout_milliseconds": 333,
            "basic.to_if_held_down_threshold_milliseconds": 333
          },
          "to": [
            {
              "key_code": "right_shift",
              "lazy": true
            }
          ],
          "to_if_held_down": [
            {
              "key_code": "right_shift"
            }
          ],
          "to_if_alone": [
            {
              "select_input_source": {
                "input_source_id": "^com\\.apple\\.keylayout\\.ABC$",
                "language": "en*"
              }
            }
          ]
        },
        {
          "type": "basic",
          "conditions": [
            {
              "input_sources": [
                {
                  "input_source_id": "^com\\.boshiamy\\.inputmethod\\.BoshiamyIMK$",
                  "language": "zh*"
                }
              ],
              "type": "input_source_unless"
            }
          ],
          "from": {
            "key_code": "right_shift",
            "modifiers": {
              "optional": ["any"]
            }
          },
          "parameters": {
            "basic.to_if_alone_timeout_milliseconds": 333,
            "basic.to_if_held_down_threshold_milliseconds": 333
          },
          "to": [
            {
              "key_code": "right_shift",
              "lazy": true
            }
          ],
          "to_if_held_down": [
            {
              "key_code": "right_shift"
            }
          ],
          "to_if_alone": [
            {
              "key_code": "spacebar",
              "modifiers": ["right_control", "right_option"],
              "hold_down_milliseconds": 1
            }
          ]
        }
      ]
    }
  ]
}