FunnelWeb is distributed under a GNU license, and you are free to modify the source code and distribute modified copies (see Section 5.6). However, there are good reasons why you should avoid doing this.
For these reasons I request that you do not distribute modified versions of FunnelWeb, particularly versions with a modified language. However, if you must distribute a version with a modified language, please change its name (i.e. from ``FunnelWeb'' to something else). Please also allocate a new file extension to replace ``.fw'' as the extension for source files written in the modified language.
For more information, refer to the FunnelWeb Hacker's Manual.