IDK if this issue still around but i could not find the solution anywhere, so i dig into this issue for a while and discovered how to install Spore on a different language. I don't know if it will work for non windows pcs, but i am sure mac or linux have their own procedures to modify the required settings.
1 - Uninstall or don't install spore just yet.
2 - go to control panel > Region > Administrative tab > language for non-Unicode programs > Change system locale = change it to whatever language you want the game to be.
3 - you will be required to restart your pc before the new setting take place. So just do it.
4 - After the restart you can (re)install Spore in the language of your choice.
obs: IDK if you have to keep the non unicode settings after the game install but you should be able to revert it without affecting the game.