Word replacements not working on Joomla
On a Joomla 3.8.8 system with CiviCRM 5.1.2 Word Replacements have no effect.
This was working when the system was on 4.6 before upgrading. Word Replacements are working on a 5.1.2 system with Drupal so it may be specific to Joomla.
To upload designs, you'll need to enable LFS. More information