Ok, updated the parser to include localization options. Download link is in the OP.
With this update the tool is now dual-language with English and Japanese. With thanks to Naoya Takana for providing translations.
To change language, simply click the drop-down menu in the top-right as shown:

Other changes:
- Re-sized the text area so you can now see all of its output at once. No more awkward scrolling!
- Moved the checkbox objects to the top of the window
- The file is now read into memory before all other options are carried out on it. This gets rid of an issue where the parser failed to operate if the file it was reading was deleted/renamed before it was parsed.
- The text area's output now updates its contents when you check/uncheck the "Output Parts Info" button.
That's all that's new in this version. I realise I'm not updating this tool often, however I don't think this is the end of my work on this either.
Things I'd like to do for it some day:
- Update the text databases. Right now it isn't feasible as I no longer have access to the same text files I did back when we had control of the english patch. I may need to work out a new solution for this. Note that this won't solve issues with unknown NPC costume parts as those are often unique unaccessible items with no names anyway.
- Prettify the text output a bit. Its a bit of a mess right now.
- Reverse parsing as requested. As I said this is in principal feasible but I'm quite intimidated by it! I was reluctant to do it before as private server efforts were in their infancy. Seeing as things still seem to be going on that front I figure it'd be cool if you could use the character creator to make custom NPCs for server content. So definitely got it in mind.
- Perhaps add other little character related features like race/sex change? Would require new UI elements.
These are not promises, merely ideas if I ever want to update this tool again in the future.