OK, Please follow this step by step:
1. In en-GB.php and all other language files, at the bottom, add 2 new definitions for "EXTRAS" and "Extras Total" like this:
define('_JOMRES_AJAXFORM_CUSTOM_JEXTRAS_TITLE','EXTRAS');
define('_JOMRES_AJAXFORM_CUSTOM_JEXTRAS_TOTAL','Extras Total');
2. edit dobooking.class.php and at approx line 971 you see "function makeOutputText()". Go at the end of this function at approx line 1064, right before "return $output;" and add:
$output['JEXTRAS_TITLE']=$this->sanitiseOutput(jr_gettext('_JOMRES_AJAXFORM_CUSTOM_JEXTRAS_TITLE', _JOMRES_AJAXFORM_CUSTOM_JEXTRAS_TITLE));
$output['JEXTRAS_TOTAL']=$this->sanitiseOutput(jr_gettext('_JOMRES_AJAXFORM_CUSTOM_JEXTRAS_TOTAL', _JOMRES_AJAXFORM_CUSTOM_JEXTRAS_TOTAL));
3. In dobooking.html and dobooking_srp.html (located in /jomres/remote_plugins/je_mira/frontend) where you see the untranslatable/hardcoded text "EXTRAS" and "Extras Total", replace that text with {JEXTRAS_TITLE} and {JEXTRAS_TOTAL}
I think this is it...