@gulli: Wich version of RISC OS do you use? On RISC OS Select and Adjust (and probably ROS4 and ROS5, but I haven't checked that) you can easily switch keybaord layouts from within the system configuration (Input -> Keyboard). If you often need to switch the layout I suggest you get WimpBar2 or a similar application/file launcher, create an obey file for each language containing the command *country followed by one of the supported *countries (currently 37 on ROS 4.39).
As for the other issues, RISC OS Ltd. has put up information where to obtain territory modules containing settings for non-UK locations on their select website. And thanks to a4com, these are even free. With most commercial OSs, you have to pay a hefty extra for localised versions. And with Windows, you don't even get the choice wich language you want the OS in, you are stuck with the one you purchased. With RISC OS and all applications wich support its territory system, it is simply a matter of setting a different territory in the system configuration and doing a quick reboot, and everything that has a localised messages- and resource- or template-file will appear in the local language. And because there are free editors for these files, everyone can simply do their own translation.