Ouch!
Changing the functions names (as shown in Reference) isn't so hard.
But changing the language itself, like the if/else/for/class/etc. and even worse the symbols, is very hard, next to impossible (I wouldn't try it, unless paid for that! ).

If you are courageous, knowledgeable and have lot of free time, I would recommend to take a look at the .g files in the source: these are grammar files processed by the Antlr library and used by Processing to pre-process the .pde files to transform them to .java files. Perhaps you can modify and extend them to do the job...

An alternative is to have your own pre-processor, less smart, but with more risks: if you change the occurrences of falls in the source, you have at least to take care of not changing them in strings (and in comments if you want).

Beside, that's just my opinion, but I think translating a programming language is often a bad idea, unless you target a very young, amateur public. Microsoft translated Visual Basic to some language and it led to lot of issues. And in an era where Internet is so widespread, making a nice language from an existing one cuts off your public from available resources (this forum, existing code everywhere, etc.).

That's certainly possible, the easiest method to do it with a Tool would be to have the tool grab the text of the code, then have the tool do the conversion from your dialect before sending it to the preprocessor. Then call the compile and run commands internally. It's a little tricky, but not nearly as difficult as writing a preprocessor for your language.

Thank you, Fry and blausand.

I just finished the project. After some Help of a few people the Editor works fine. There are still some bugs and the editor for Windows and Linux is not jet finished, but on Mac it works fine.
It is also possible to manipulate the new language with just a text editor.
Here is the link to the project.
http://stefanbaltensperger.ch/