I'm not sure of the simplest way to do this en masse... But theoretically, all you have to do is go into each individual planet mod (and their dependencies, if necessary), extract the zip file and check the locale/en folder; this is where the English names for everything resides. From locale/en, you would have to copy each of the cfg files into a new folder, locale/zh-CN (I think?), and then change all of the values on the right-hand side to whatever they should be in Chinese. So for example, you might see:
internal-recipe-name=Name of Recipe
internal-entity-name=Name of Entity
In which case, you would change the Name of Recipe and Name of Entity values. After doing this for everything you want translated, you'd move onto the next planet mod/dependency and continue down the line. It would be.. very time-consuming, to say the least.
What you do with the translated cfg files afterwards is up to you, but ideally, you could offer them to the original planet mod authors to integrate the translations into their mod. You could also release the pack of cfg files as a standalone mod, similar to this mod, which was made for AAI. Or just keep them for personal use; no pressure.
