Project files have been updated to version 12.0 (codename: “Time of Your Life”), and the first post has been updated. Please PM me for temporary download links until the files are available at some more permanent locations.

Rough summary of changes from 11.0 to 12.0:

New languages: Catalan, Basque (both thanks to laozi), and Slovak
New Japanese translation (thanks to schorman13)
New Korean translation for Star Wars (thanks to Kaz47)
Included titles-only subtitles to go with the Galician dub (again, thanks to laozi)
Improvements to the Castilian Spanish subtitles (yet again, thanks to laozi!)
Improved Finnish translations (thanks to LexX)
Improved Swedish translations (thanks to Rondan)
Finally adding this much-requested feature, every official pre-1997 version of the trilogy is now fully supported in all supported languages. This includes four subtitle variations for Star Wars, and two for Empire. Multiply that by a lot of languages, and that’s just a ton of subtitles. I was able to do this without driving myself crazy by making the whole process automated, using “fragment files”, which are a sort of multi-target subtitle diff file I created for this purpose. The fragment files include translations for all of the subtitle-worthy differences for all of the pre-1997 versions of the films. Using a script, you can quickly assemble subtitles (in SUP or SRT format) for any pre-1997 version of the films using the original stereo/surround subtitles as a baseline, then adding the appropriate portions of the fragment file, and making various timing adjustments. Any new languages added to the project will need to include fragment files in addition to the regular stereo/surround SRT files. Script-generated SRT files are included in all supported languages for every pre-1997 mix, but to conserve space, only the original stereo/surround versions are provided in SUP format. You can, however, easily assemble SUP files for any version you prefer. To avoid the confusion of so many different versions, each subtitle variation has its own subfolder (thanks to laozi, RashadShehadeh, Feallan, ccfilms, LexX, ZIPC, Leoj, Rondan, Harmy, daboka, Mavimao, Kaz47, and schorman13).
Created a new subtitle rendering script, no longer relying on ImageMagick+Pango, and instead simply rendering subtitles in a Chromium-based web browser. The advantage of the new script is that it no longer relies on running outdated versions of ImageMagick and Pango, and its cross-platform behavior is also much improved (there are no longer any scripts that can’t be rendered on Windows, for example). ImageMagick is still heavily used, just without the Pango integration. Many minor bugs in the old script were fixed during the rewrite, and it’s quite likely some new ones were also created! One known issue is that Chromium-based browsers tend to create stray processes that over time bog down a machine, so if you do run this script, I recommend rebooting your computer afterward, just to be safe.
Bulgarian and Macedonian got better localized Cyrillic text than the current released versions of the Noto Sans fonts can provide out-of-the-box.
Most languages got some very minor changes, typically just timing improvements
Pre-rendered graphical NTSC DVD subtitles are no longer included with the project files. DVD subtitles are still supported and can be created using the provided instructions.
The cyrl-compat script was removed. It turns out it was not really necessary after all.
Pre-built Windows utilities are now 64-bit executables
Python scripts now require Python 3.4 or later
As part of some general language code housekeeping, the language codes for Mandarin and Cantonese have been changed for consistency with the rest of the project. The “zho-” prefix has been dropped, and now these languages use the plain ISO-639-3 language code (cmn and yue, respectively).
Most files that are not actually usable subtitles have been moved into the resources folder, and the resources folder is now better-organized
Most folder names have been lowercased, to make things a little easier on people working with case-sensitive filesystems
Some dubs currently have missing sections (due to damaged tapes or other factors). “Titles” subtitles for those languages now also subtitle those missing lines, whenever a text translation is available (currently only for Cantonese and Galician). If the missing sections in those dubs are ever restored, Project Threepio will update the “titles” subtitles to remove the redundant translations.
Project Threepio’s extensive readme.html file has been given a visual overhaul to be less overwhelming to newcomers. It now uses expanding sections to display only the information you choose to see, rather than jumping to sections in one huge wall of text. It also now includes some command-builder scripts, so that you don’t have to hand-edit the commands to customize them for your needs. Displaying the file also now does not rely on any files from Project Threepio’s resources folder (i.e. images). This should help when Project Threepio is distributed in an incomplete form, which is a fairly common scenario – although you may still need some of those resource files to actually perform the tasks described in the documentation.
The bidi-compat script has been improved to no longer require any text-specific workarounds for any existing Project Threepio subtitles. This increases the chances that it will produce good results out of the box with any future BiDi text.
Potentially slow bulk image manipulation scripts now include progress indicators and spinner animations
The project now includes a changelog (changes.html), including changes for every past release (thanks to pmc3)