My requirement is when browser is in English, Title column in Content Type (content type is attached with list) is rename as "Last Name" and when in German, it should be "Nachname". My below code ran successfully and can rename only in English, but I wonder how to rename in German as well.
$site = new-object Microsoft.SharePoint.SPSite("site collection url")
$web = $site.OpenWeb()
$ct=$web.ContentTypes["CT1"]
$field = $ct.Fields.GetFieldByInternalName("Title")
$ct.FieldLinks[$field.Id].DisplayName ="Last Name"
$ct.Update();