@Smanar Thanks you for your patience!  
I may just have found a working combination by cutting/pasting bits and pieces from the Ikea TW Bulb DDF! Can you check if you see anything strange? It seems it works now: I can add a new Aqara/Lumi bulb, turn it on/off, dim it and set the color temp now.
I re-opened the Aqara PR (and also opened a PR for 2 new Ikea lights DDFs).
{
  "schema": "devcap1.schema.json",
  "manufacturername": "$MF_LUMI",
  "modelid": "lumi.light.aqcn02",
  "product": "lumi.light.aqcn02",
  "sleeper": false,
  "status": "Gold",
  "path": "",
  "subdevices": [
    {
      "type": "$TYPE_COLOR_TEMPERATURE_LIGHT",
      "restapi": "/lights",
      "uuid": [
        "$address.ext",
        "0x01"
      ],
      "items": [
        {
          "name": "attr/id"
        },
        {
          "name": "attr/lastannounced"
        },
        {
          "name": "attr/lastseen"
        },
        {
          "name": "attr/manufacturername"
        },
        {
          "name": "attr/modelid"
        },
        {
          "name": "attr/name"
        },
        {
          "name": "attr/swversion"
        },
        {
          "name": "attr/type"
        },
        {
          "name": "attr/uniqueid"
        },
        {
          "name": "config/colorcapabilities",
          "refresh.interval": 84000
        },
        {
          "name": "config/ctmax",
          "refresh.interval": 84000
        },
        {
          "name": "config/ctmin",
          "refresh.interval": 84000
        },
        {
          "name": "state/alert",
          "default": "none"
        },
        {
          "name": "state/bri",
          "refresh.interval": 5
        },
        {
          "name": "state/colormode"
        },
        {
          "name": "state/ct",
          "refresh.interval": 5
        },
        {
          "name": "state/on",
          "refresh.interval": 5
        },
        {
          "name": "state/reachable"
        }
      ]
    }
  ],
  "bindings": [
    {
      "bind": "unicast",
      "src.ep": 1,
      "dst.ep": 1,
      "cl": "0x0006",
      "report": [
        {
          "at": "0x0000",
          "dt": "0x10",
          "min": 1,
          "max": 1800
        }
      ]
    },
    {
      "bind": "unicast",
      "src.ep": 1,
      "dst.ep": 1,
      "cl": "0x0008",
      "report": [
        {
          "at": "0x0000",
          "dt": "0x20",
          "min": 5,
          "max": 1800,
          "change": "0x00000001"
        }
      ]
    },
    {
      "bind": "unicast",
      "src.ep": 1,
      "dst.ep": 1,
      "cl": "0x0300",
      "report": [
        {
          "at": "0x0007",
          "dt": "0x21",
          "min": 5,
          "max": 1800,
          "change": "0x00000001"
        },
        {
          "at": "0x0003",
          "dt": "0x21",
          "min": 5,
          "max": 1795,
          "change": "0x0000000A"
        },
        {
          "at": "0x0004",
          "dt": "0x21",
          "min": 5,
          "max": 1795,
          "change": "0x0000000A"
        },
        {
          "at": "0x0008",
          "dt": "0x30",
          "min": 1,
          "max": 1800
        }
      ]
    }
  ]
}
The api returns:
{
“colorcapabilities”: 0,
“ctmax”: 65279,
“ctmin”: 0,
“etag”: “0ee9f2b195593b366e5b2007de55c566”,
“hascolor”: true,
“lastannounced”: null,
“lastseen”: “2022-09-08T18:42Z”,
“manufacturername”: “LUMI”,
“modelid”: “lumi.light.aqcn02”,
“name”: “Color temperature light 14”,
“state”: {
“alert”: “none”,
“bri”: 148,
“colormode”: “ct”,
“ct”: 327,
“effect”: “none”,
“lift”: 0,
“on”: false,
“open”: false,
“reachable”: true,
“xy”: [
0.4355,
0.4079
]
},
“swversion”: “1.23”,
“type”: “Color temperature light”,
“uniqueid”: “00:15:8d:00:05:20:eb:66-01”
}