Localization
Localize editor strings and properties
Survey.Survey.cssType = "bootstrap";
Survey.defaultBootstrapCss.navigationButton = "btn btn-green";
//Create your translation
var deutschStrings = {
    p: {
        isRequired : "Wird ben�tigt"
    }
};

//Set the your translation to the locale
SurveyEditor.editorLocalization.locales["de"] = deutschStrings;
//Make this locale the current
//SurveyEditor.editorLocalization.currentLocale = "de";
//Make french locale active
SurveyEditor.editorLocalization.currentLocale = "fr";
var editorOptions = { };
var editor = new SurveyEditor.SurveyEditor("editorElement", editorOptions);

<!DOCTYPE html>
<html>
<head>
    <title>Localize editor strings and properties, SurveyJS Editor Example</title>
    <script src="https://unpkg.com/jquery"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.3.0/knockout-min.js"></script>
    <script src="https://surveyjs.azureedge.net/0.96.3/survey.ko.js"></script>
  
    <script src="https://cdnjs.cloudflare.com/ajax/libs/ace/1.2.0/ace.min.js" type="text/javascript" charset="utf-8"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/ace/1.2.0/worker-json.js" type="text/javascript" charset="utf-8"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/ace/1.2.0/mode-json.js" type="text/javascript" charset="utf-8"></script>
    <link href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/css/select2.min.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/js/select2.min.js"></script>
    <link href="https://surveyjs.azureedge.net/0.96.3/surveyeditor.css" type="text/css" rel="stylesheet" />
    <script src="https://surveyjs.azureedge.net/0.96.3/surveyeditor.js"></script>
    <link rel="stylesheet" href="https://unpkg.com/bootstrap@3.3.7/dist/css/bootstrap.min.css">
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
    <link rel="stylesheet" href="./index.css">

</head>
<body>
        <div id="surveyContainer">
        <div id="editorElement"></div>
    </div>

<script type="text/javascript" src="./index.js"></script>

</body>
</html>
.btn-green {
  background-color: #1ab394;
  color: #fff;
  border-radius: 3px;
}
.btn-green:hover, .btn-green:focus {
    background-color: #18a689;
    color: #fff;
}
.panel-footer {
    padding: 0 15px;
    border:none;
    text-align: right;
    background-color: #fff;
}

Localization

Please make a pull request of your localization to Editor Localization Files.

You have to localize the defaultStrings variable located in editorLocalization.ts

The example of localization survey js strings are here.