Hi, I have a SGS2 on GB based ROM (WIUI) and has the problem with the externalSD too. I could open the dir just fine (sdcard/external_sd) and see the files but now I tried to upload the 1.7GB file and gets a message that there is NOT enough space but I have about 8GB.
It looks like the AirDroid thinks that I have only 1.5GB free because thats the space on my internal SD card so thats the problem need to be solved ... besides this and few bugs here and there this is just ASTONISHING app!
JayM
PS: Wondering when the Czech translation will be available because - according to Your translation section - the language is already prepared.