Change "Passwords match" and "Password Strength" text on signup
The two sentences are set by Javascript (/modules/user/user.js) so for this you have to use JS too..

$(".password-strength-title").val("Test");


can replace the first one, but for the other it is more complicate. I have to look deeper.

EDIT

The info are here now I don't know if it is possible to do an alter

EDIT

Ok so for doing what you want 2 steps:

function your_module_element_info_alter(&amp;$type){
  $type['password_confirm']['#process'][] = 'your_module_form_process_password_confirm';
}


Then alter the data:

function your_module_form_process_password_confirm($element){
  $element['#attached']['js'][1]['data']['password']['strengthTitle'] = t("Test Title");
  $element['#attached']['js'][1]['data']['password']['confirmTitle'] = t("Test confirm");

  return $element;
}