I'm managed to reverse engineer the data.dat file format for Sisonoha's Ultimate Sunflower Creation, since I saw someone actually wanted to do a translation of it.
The download is here:
http://labs.astrobunny.net/downloads/USCDecrypt.zipIt is a command line tool. At the console you need to type USCDecrypt.exe C:\USC\Data.dat
where C:\USC\Data.dat is the full path to wherever your Data.dat is
and it will unpack all the files into a folder called unpacked next to your Data.dat file.
I haven't cracked open the internal files yet, and some strings also exist in the executable file itself I believe. But, hopefully this might go some way to helping you guys start your translation project.
Some image resources from the game:
