To fix the "TPL_FLEXIBLE_MORE_INFO" text problem.
Find this INI file:
/language/en-GB/en-GB.tpl_flexible_coolmart.ini
and copy-paste it to your native language's folder with this form:
/language/hu-HU/hu-HU.tpl_flexible_coolmart.ini
Then make the translation manually. (there are total 10-15 lines to translate. You can do it manually)
To fix the other product details page problem. Obviously it is a PHP error. A serious error.
Try to enable the "Error Reporting" to "Development" through Joomla Global Configuration
Attachment Pasted_Image_6_28_14__2_59_AM.png not found
and see what kind of error you will see in this page:
halmar.hu/szekek/fonoki-forgoszekek/341/prestige-vezetoi-mubor-karosszek-detail . I am guessing this issue is happening because of a plugin you have enabled. But i can't be sure what it is. Because there is no error reporting to give me a clue.
If the changing the error reporting to "Development" through Joomla Global Configuration still doesn't report any error, then look at the PHP Error Log file of your hosting. The Erorr Log file must log all the reported errors on your website.
Regards,
Support