Initializes the localization settings before entering into a scene in play mode

EditorBootScene.cs

using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEngine.Localization.Settings;
using UnityEngine.SceneManagement;

[InitializeOnLoad]
public static class EditorBootScene
{
    static EditorBootScene()
    {
        EditorApplication.playModeStateChanged += EditorApplication_playModeStateChanged;
    }

    /// <summary>
    /// The scene needs to be in the build settings so if its not we will add it and remove it again later on.
    /// </summary>
    /// <param name="scene"></param>
    /// <returns></returns>
    static bool AddSceneToBuildSettings(Scene scene)
    {
        var scenes = EditorBuildSettings.scenes;
        for (int i = 0; i < scenes.Length; ++i)
        {
            var s = EditorBuildSettings.scenes[i];
            if (s.path == scene.path)
                return false;
        }

        ArrayUtility.Add(ref scenes, new EditorBuildSettingsScene(scene.path, true));
        EditorBuildSettings.scenes = scenes;
        return true;
    }

    /// <summary>
    /// Remove the scene from the build settings
    /// </summary>
    /// <param name="path"></param>
    static void RemoveScene(string path)
    {
        var scenes = EditorBuildSettings.scenes;
        for (int i = 0; i < scenes.Length; ++i)
        {
            var s = EditorBuildSettings.scenes[i];
            if (s.path == path)
            {
                ArrayUtility.RemoveAt(ref scenes, i);
                EditorBuildSettings.scenes = scenes;
                return;
            }
        }
    }

    static void EditorApplication_playModeStateChanged(PlayModeStateChange obj)
    {
        // Entering play mode so load the boot scene
        if (obj == PlayModeStateChange.ExitingEditMode)
        {
            if (!EditorSceneManager.SaveCurrentModifiedScenesIfUserWantsTo())
                return;

            // Record the current scene so we can go back to it once we have booted.
            var scene = EditorSceneManager.GetActiveScene();
            SessionState.SetString("current-scene", scene.path);
            SessionState.SetBool("remove-scene", AddSceneToBuildSettings(scene));

            // Create an empty scene to initialize in
            var newScene = EditorSceneManager.NewScene(NewSceneSetup.EmptyScene, NewSceneMode.Single);
        }
        else if (obj == PlayModeStateChange.EnteredPlayMode)
        {
            // Wait for initialization and then switch to the scene
            if (LocalizationSettings.InitializationOperation.IsDone)
                LoadScene();
            else
                LocalizationSettings.InitializationOperation.Completed += (_) => LoadScene();
        }
        else if (obj == PlayModeStateChange.EnteredEditMode)
        {
            // When entering edit mode revert back to how things were previously.
            var path = SessionState.GetString("current-scene", null);
            EditorSceneManager.OpenScene(path);

            if (SessionState.GetBool("remove-scene", false))
                RemoveScene(path);
        }
    }

    static void LoadScene()
    {
        var path = SessionState.GetString("current-scene", null);
        EditorSceneManager.LoadScene(path);
    }
}