using System;

using System.Collections.Generic;

using System.Linq;

​

using Newtonsoft.Json;

class Program

{

    static void Main(string[] args)

    {

        string input = @"{

    ""play_classic"": [

        { ""english"": ""PLAY CLASSIC"" },

        { ""spanish"": ""JUEGO CLÁSICO"" },

        { ""portuguese"": ""JUEGO CLÁSICO"" },

        { ""russian"": ""IGRAT' V KLASSICHESKUYU"" }

    ],

    ""play"": [

        { ""english"": ""PLAY"" },

        { ""spanish"": ""JUEGO"" },

        { ""portuguese"": ""JUEGO"" },

        { ""russian"": ""IGRAT'"" }

    ],

    ""classic"": [

        { ""english"": ""CLASSIC"" },

        { ""spanish"": ""CLÁSICO"" },

        { ""portuguese"": ""CLÁSICO"" },

        { ""russian"": ""KLASSICHESKUYU"" }

    ]

}";

        var resultRaw = JsonConvert.DeserializeObject<Dictionary<string, List<Dictionary<string, string>>>>(input);

        var resultFlattern = resultRaw.ToDictionary(

                                        x => x.Key, 

                                        x=> x.Value.SelectMany(trd=> trd)

                                        .ToDictionary(kvp=> kvp.Key, kvp=> kvp.Value)

                                    );

​

​

        // given the button play_classic and the langue "portuguese"

        var buttonName="play_classic"; var language= "portuguese";

        if(resultFlattern.TryGetValue(buttonName, out Dictionary<string, string>  allTrads))

        {

            if(allTrads.TryGetValue(language, out string traduction)){

                Console.WriteLine($"Traduction for button [{buttonName}] in [{language}] is : [{traduction}]") ;

            }

            else

            {               

                Console.WriteLine($"Cant find tanslation for button : [{buttonName}] in [{language}]") ;

            }

        }

        else{ 

            Console.WriteLine($"Cant find tanslation for button : [{buttonName}]");

        }

        //Direct access:

        Console.WriteLine($"Direct access : [{resultFlattern[buttonName][language]}]"); 

    }

}