A workaround I am now using is manually reformatting my texts with notepad++
. You have to go to TextFX->TextFX Edit->ReWrap Text. A line width of 44 characters is fitting for medium font in landscape mode.
Another way of reading eBooks is of course saving the pages as single jpg files and using the picture viewer, or you can create a flash file from a pdf and run it on the SPINN (only for smaller files up to around 1MB)
Anyways, I like the text app best. Still not sure about the language selection option though.