widget read more link, error

in juni 2018 you gave my this solution but i didn’t want to mess with my permalinks on a live website. I’ve tried it now on a demo site, but it doesn’t work

/*
Please paste it to your WordPress theme functions.php

DON’T FORGET TO SAVE PERMALINKS SETTINGS.
*/
function __ai1ec_custom_slug_name( $translations, $text, $domain ) {
if (
AI1EC_PLUGIN_NAME !== $domain ||
‘event’ !== $text
) {
return $translations;
}
return ‘ai1ec-event’;
}
add_filter( ‘gettext’, ‘__ai1ec_custom_slug_name’, 10, 3 );