Cannot find a word/definition to translate
These problems usually occur when you are using an outdated translation of the component or module, meaning that the .INI Translation File for your Language is not updated to the version of the component.
It is necessary to compare your .INI Translation File with the original en-GB translation to copy the missing translation and put it in your language file for translating it.
You should first understand if the missing translation is used for a module or if it's used for the component. Locate the corresponding en-GB .INI file and compare it with the one for your language. At the bottom of the file you will find some missing definitions. Copy all of them and paste them onto your .INI file. The last step will be translating the English definitions that were missing, into your Language.
For more details please visit the Documentations page, Translations section.