All Form2Content components, modules and plugins use the Joomla native language mechanism. This means you can override them without loss if changes if done conform the Joomla override method.
What happens during an upgrade of F2C?
During a Form2Content upgrade the language files are overwritten (replaced). Any custom translations will be lost unless you use the Joomla override system.
Where can I find new language strings after an upgrade?
To keep things as simple as possible we add new F2C language strings at the BOTTOM of the LANGUAGE FILES separated with VERSION HISTORY. This way you can copy/paste your (backup) changes of the language files if you made any.
Where can I find the F2C language files?
All language files are saved conform Joomla best practise and can be found in:
administrator/language/en-GB (which files depend on the F2C extensions)
language/en-GB (which files depend on the F2C extensions)