Here a patch to make error messages in checkout form translatable
function uc_textfield($title, $default = NULL, $required = TRUE, $description = NULL, $maxlength = 32, $size = 32) {
if (is_null($title) || empty($title))
return NULL;
$textfield = array(
'#type' => 'textfield',
'#title' => t($title), // call title with t function
'#description' => $description,
'#size' => $size,
'#maxlength' => $maxlength,
'#required' => $required,
'#default_value' => $default
);
return $textfield;
}
