SharePoint 2013 multilingual libraries

I have created custom SharePoint web template. It contains custom libraries, events, site columns, content types, etc...

Now I need to implement it to multilingual, so I can use English and German.

What I have done:

I've been able to translate all from English to German, except site columns. (I don't know have I used good way to translate these names).

Example here, Description and Hide are my custom columns. If I install language pack all other fields change except my custom columns.

I use my custom fields in my events:

public static void CopyItem(SPItemEventProperties properties, SPList list)
    {
        string documentUniqueName = null;

        try
        {
            if (list != null)
            {
                properties.Web.AllowUnsafeUpdates = true;
                documentUniqueName = properties.ListItem.UniqueId.ToString();
                SPListItem listItem = list.Items.Add();

                listItem["DocumentName"] = documentUniqueName;
                listItem["Title"] = properties.ListItem["Title"];
                listItem["Description"] = properties.ListItem["Description"];

                // etc...

How should I translate to custom site columns? Should I create new column and change my event code somehow or?

This is my first time, when I'm doing multilanguage web template. What are best practices to create multilingual SharePoint web template? So, I can avoid pitfalls.

Thank you!