The tab for the hungarian language should be available as soon as one of your shops hast this locale.
If it is missing, you need to create a snippet in the database with the combination of the language and the shopID 1. Somethink like this:
INSERT INTO `s_core_snippets` (`id`, `namespace`, `shopID`, `localeID`, `name`, `value`, `created`, `updated`, `dirty`) VALUES ('0', 'backend/activate/skeleton', '1', (SELECT id FROM `s_core_locales` WHERE `locale` LIKE 'hu_HU'), 'WindowTitle', 'Cache leeren', '2019-06-06 08:59:44', '2019-06-06 08:59:44', '0');
As soon as there is one snippet with the combination locale + shopID1 the tab will be shown.