Just making sure... but he IS talking about the editor position right? And not just editing files? Anyways...
If your hackers/tool people did their jobs right, you should get a file compatible with a decent translation work environment that will let you have views of the original line, translated lines, and comments.
I view the editor's job as composed of these 4 main parts:
1. Ensuring correct mechanics
Spelling, grammar, tense, style. It is mainly the editor's job to make sure that these elements are done correctly and consistently.
2. Checking consistency
As in the broad sense of making sure that conventions are followed consistently throughout the work. If a character is supposed to speak in a certain way, or if there is a certain convention set, for example for use of capitalization while stuttering, then the editor must help check that this is being adhered to when appropriate.
3. Sanity checks
That is to say, making sure your translator didn't fuck up and write something incomprehensible due to an interpretation error. Many such errors can be caught just by recognizing that a line doesn't make sense in context, even if you don't know Japanese.
4. Rewriting awkward sentences
Many times translators will produce a sentence that has the right meaning, but doesn't sound quite right to a native English speaker. It mainly falls to the editor to take these sentences and rewrite them to sound natural. Consult with your translators or TLC if you are unsure if you are capturing the right meaning in your edits.
In my experience 4 is the hardest to master. It is not something you really learn until you start editing translations. The others are more or less an issue of being attentive and having a solid grasp on English and writing.