Your design of a bilingual Qwerty layout makes sense. It adds Spanish to the Qwerty, but does not make it any worse for English texts. Such a qwerty variant would be ideal for North America, for example

I believe that a trilingual layout can be modified from keyboards like TOHKBD rev. 2. By adding to their dedicated keys the Ç and Ñ characters and the dead-key accents of the Spanish, Portuguese and Catalan languages, as well as¿ ¡ ª º · characters as the combinations with the blue "Chr" key, the same keyboard would be suitable for Spain and Portugal, as well as practically all Latin America. The keyboard might be suitable also for French texts (but for French it would be more limited and less standard than the Canadian bilingual Qwerty, for example). Naturally also English could be written easily on the Spanish+Portuguese+Catalan Qwerty variant. I may publish my draft in the thread of http://talk.maemo.org/showthread.php?t=94303