I've just created a simple front-end program that will re-import the nations.txt into an existing game.
Download it from
http://www.bourtonville.co.uk/OOTPEditor1005.zip
Notes:
1. This program makes changes to world.dat, nations2.dat and ethnicities.dat - it creates a backup of each of them when it's run so if it does mess up, use the latest backup of each to let the game continue
2. It doesn't allow for adding or deleting of nations from the game yet. It will replace the details for each nation id from the same line in the nations.txt. You can alter any of the columns in nations.txt (name, level, ethnicity splits) and these will be saved to the database. If you add a new nation id that doesn't already exist it'll be ignored. If you add the nation in game you should then be able to add it to nations.txt
3. Changes to cities are not loaded as the cities.txt does not have an ID field in it and altering the number of cities could lead to teams and players coming from strange places.
4. It doesn't check if the percentages add up to 100
5. Always take a copy of your nations.txt and ethnicities.txt before changing them
6. You must not be in the game you want to alter when running this due to the auto-save on exit functionality. Save your game when you want to make the changes, and exit OOTP, then run the update and restart OOTP.
Installing.
Download the zip in the message and unzip to a folder. Go to that folder and double click OOTPEditor.application (you will need the .NET Framework v2 to run this)
There are two text boxes - the top one is the saved game directory that you want to alter (click on the ... to the right to open a folder dialog), and the bottom one is the text file directory (normally My Documents\Sports Interactive\OOTP Baseball 2007\data\database - ie where the nations.txt files etc are)
Then click on Import Nations to import nations.txt to alter the nations2.dat and world.dat (this will affect future name creation), or Import Ethnicities to import ethnicities.txt to alter the ethnicities.dat file.
Future enhancements.
1. Ability to re-import names. Have tried to do this, but the default names text files have problems in them that mess up when you read them in (for example there are two Beau's in language set 0, and St. Andrew only has one number in the names.txt and is therefore either lacking a frequency or a nameset id)
2. Ability to add/remove nations. This would involve going through all the players, teams and staff and making sure that they didn't belong to a non-existent place (though where you would move them to as a default is a different question)
3. Picking up files based on the year of simulation. The world.dat has the current simulation date in it, so it could be enhanced to look for files such as nations_1901.txt, nations_1902.txt, etc...