Hi,
I spend some time doing the translation but I think it's fine.
Following wroot instructions what we should do is:
1. Open \archivos de programa\spark\plugins (or your installation directory)
2. Using your favorite archiver (mine is winrar) open fastpath.jar, then browse to lib and again open plugin-classes.jar and browse to i18n folder
3. What I did there was erase the original fastpath_i18n.properties file and put mine, the one which is translated.
4. Close saving changes. Enjoy your plugin translated.
This is what I did and it works really fine. Some things were not traslated, I don't know why. e.a. tooltips in transfer,invite and co-browse buttons.
Esta herramienta realmente es muy buena, vale la pena trabajar en ella.
Greetings