如何使用另一个词典的内容替换缺失的内容？

所以，我正在为一个游戏进行翻译，并且我有不同的词典。如果一个翻译在某个语言中不存在，我想将其设置为英语翻译。但我尝试过的每种组合词典的方法都非常低效。

这里是一些简化的例子

local translation-sr = {
    Buttons = {
        Confirm = "Потврди";
        Submit = "Унеси";
    };
    Countries = {
        Bloxell = "Блоксел";
        USA = "Сједињене Америчке Државе";
    };
    Firearms = {
        Manufacturers = {
            GenMot = "Џенерални Мотори";
            Intratec = "Интратек";
            TF = "ТФ Оружје";
        };
    };
};

local translation-en = {
    Buttons = {
        Confirm = "Confirm";
        Purchase = "Purchase";
        Submit = "Submit";
    };
    Countries = {
        Bloxell = "Bloxell";
        USA = "United States";
    };
    Firearms = {
        Manufacturers = {
            GenMot = "General Motors";
            Intratec = "Intratec";
            TF = "TF Armaments";
        };
    };
    Languages = {
        Belarusian = "Belarusian";
        English = "English";
        French = "French";
        German = "German";
        Italian = "Italian";
        Russian = "Russian";
        Serbian = "Serbian";
        Spanish = "Spanish";
    };
};