Hi,
Right the translation framework is only designed to handle the translation of pages in AEM. Assets are much harder when it comes to handle translation. The easiest way is if the file types support multi-language by definition, but that's hardly the case. The next obvious
way would be to have a dedicated file for each language, but that can cause a lot of overhead because then you need to handle much more assets.
There are definitely a lot of cases and approaches you can think of. But at first you need to define how the translation process should look like conceptually, and then you can start to create tool support and automation for it.