Yes, that's probably it. There is a hacky way you could try instead:
Create a file called e.g. Wikinames.i18n.php, with the following content:
<?php
$messages = array();
$messages['en'] = array(
'project-localized-name-translatewiki_net-bw_' => 'TranslateWiki',
// other project names here if you have more
);
// Translations for other languages here if relevant, e.g. $messages['fr'] = array( ... etc
Then add the following to LocalSettings.php
$wgExtensionMessagesFiles['Wikinames'] = 'path/to/Wikinames.i18n.php';