Where do I put it to get it into your RSGallery2 builds later on?
Where do I find the very latest english language file for RSGallery2 2.X.X? (I want that one as base for my translation, and the link at the wiki does not work)
One more question; Is the language files under /var/www/album/language/ and /var/www/album/administrator/language/ identical? Or should they differ?
On the first two questions: see
http://rsgallery2.net/component/option,com_smf/Itemid,17/topic,15336.msg39773#msg39773 (people put their translated files there and there is a location mentioned where you can find the latest english language file).
Last question: I found the language files in /JOOMLAROOT/administrator/language/.../ and /JOOMLAROOT/language/.../ identical, and there is a file needed at both places.
There seems not to be any RSGallery2 language files for the default english language in Joomla 1.5!?!
If my memory serves me: I thought that when I installed Joomla with a second language that I could see the language dirs. Languages not installed on Joomla are not installed for RSGallery2. In my case: I had Joomla 1.5.4 with en-GB and nl-NL, so with RSGallery2 I got en-GB and nl-NL folders in both language folders (and error messages for all other languages). Just as you mention, when I had only one language installed in Joomla 1.5.x I couldn't find the language folders (and thought I was crazy?).