So buying a Class 4 instead of a Class 10 card was actually a good decision (the salesperson of course wanted to sell me Class 10 which was a bit more expensive).
Well, after checking the card on a computer, there was no "Chinese" folder: just one ".modest" and another "MODEST~1" folder (which are now displayed on N900 as well, at least after a reboot). Not sure if they're both supposed to be there (as far as I remember, the "~1" format would be used to represent the LFN file and folder names to be accessed in pre-LFN systems), so maybe it's a (Modest?) bug creating two separate folders.