Indeed, my solution wouldn’t work.
I have however found another faulty translation string, also missing some ‘s’, in this translation:
#. translators: 1: Opening bold tag, 2: Closing bold tag.
#: gtranslate.php:2100
msgid "You can %1$sincrease%2$s your international %1$straffic%2$s by upgrading your GTranslate."
msgstr "Puedes %1$aumentar%2$ tu %1$stráfico internacional%2$ actualizando tu GTranslate."
Hi, I was about to report this same issue. It seems to be caused by a malformed translation of one of the admin notices for the Spanish language.
You can fix it yourself by opening the file wp-content/languages/plugins/gtranslate-es_ES.po and replacing the line 485:
msgstr "Puedes disfrutar de %1$traducciones automáticas con redes neuronales%2$s con una calidad comparable a la humana actualizando tu GTranslate."
With this one:
msgstr "Puedes disfrutar de %1$straducciones automáticas con redes neuronales%2$s con una calidad comparable a la humana actualizando tu GTranslate."
For the plugin author, it seems the translator miss-wrote the first sprintf param, missing the last s.
