Parsing complex JSON table

Hi mjsl5e1 

I guess there're different ways one can go about this, this PQ script will create a column named 'Tables' containing the tables in the format you asked. Now you have to see if it works on your real data and possible have to tweak it

let
    jsonData  = "{
  ""TABLE1"": [
    {
      ""Field1a"": ""Value1a"",
      ""Field1b"": ""Value1b"",
      ""Field1c"": ""Value1c""
    },
    {
      ""Field2a"": ""Value2a"",
      ""Field2b"": ""Value2b"",
      ""Field2c"": ""Value2c""
    },
    {
      ""Field3a"": ""Value3a"",
      ""Field3b"": ""Value3b"",
      ""Field3c"": ""Value3c""
    }
  ],
  ""TABLE2"": [
    {
      ""Field1a"": ""Value1a"",
      ""Field1b"": ""Value1b"",
      ""Field1c"": ""Value1c""
    },
    {
      ""Field2a"": ""Value2a"",
      ""Field2b"": ""Value2b"",
      ""Field2c"": ""Value2c""
    }
  ],
  ""TABLE3"": [
    {
      ""Field1a"": ""Value1a"",
      ""Field1b"": ""Value1b""
    }
  ],
  ""TABLE4"": [
    {
      ""Field1a"": ""Value1a"",
      ""Field1b"": ""Value1b"",
      ""Field1c"": ""Value1c""
    },
    {
      ""Field2a"": ""Value2a"",
      ""Field2b"": ""Value2b"",
      ""Field2c"": ""Value2c""
    }
  ],
  ""TABLE5"": [
    {
      ""Field1"": ""Value1"",
      ""Field2"": ""Value2""
    }
  ]
}",

json_parsed = Json.Document(jsonData),

ListToTable = Record.ToTable(json_parsed),

ZippedList = Table.AddColumn(
            ListToTable, "ZipList", 
            each 
                  List.Zip(
                    List.Transform([Value], each Record.ToList(_))),
            type list
            ),

  AddedCustom = Table.AddColumn(
                        ZippedList, "Tables", 
                        each let
                              FieldsNumber = List.Max(List.Transform([ZipList], each List.Count(_))),
                              Headers = List.Transform({1..FieldsNumber}, each "Col" & Text.From(_)),
                              Records = List.Transform([ZipList], each Record.FromList(_, Headers)),
                              Tbl = Table.FromRecords(Records)
                            in
                              Tbl,
                        type table)
in
    AddedCustom