Hello Jiri,
Thanks for your answer !
1 - about accessing the same pages with 2 URL : I have worked on it today, so I did realise it is coming from Joomfish. I am quite surprised you have not met this (as a problem I mean) before. Duplicate content is one of the major issue for Google. It will set you back many pages in its ranking if its find this, because it believes you are trying to make "false" content, pretending to have more content than you really have. You are much better off not having any URL rewriting at all (I mean index.php?option=com_content&id=...) than having duplicate content !!! There are tons of information on this on the internet, especially on SearchEngineWatch or Webmasterworld
I have worked out a fix today. Not in the Fish because it is too complex, but I have made a workaround in ARTIOSEF. Basically, I check if the language requested is the default language, and if so, I just discard the lnaguage information, so as to come back to the normal URL. Only URLs for language #2, #3,... have language infromation appended.
2 - Well I have been working on this as well, and I do not understand why titles and aliases are not translated. Joomfish (1.7) adds its own database laye, which replaces Joomla own. When anyone queries the DB for content, menu items, category name or whatever, the request is processed transparently to return the content version in the right language. This mechanism does not work when ARTISEO places its request for titles (in getContentTitles()), and I cannot figure out why for now. if you have any pointer to why it is not wokring ?
I'll keep working on it, as I badly need rewritten URL AND Joomfish. I'll send you the fixes for 1 when I know if 2/ is feasible.