A strange thing happened - after i executed this command, i was able to create and delete a folder - i thought this solved the problem so i changed the "mount.sh" script and added this command as the first line after the "then" line which comes after the mount command and tried to unmount and mount again from hen.
However, i am not able to mount it again in read/write mode - even if i returned the script to its original form and retry your command.

I tried also to connect the usb key to my laptop and scan for errors - just to make sure that nothing was wrong because of the dismount, but still after this i cannot connect it again in write mode using hen and getting the "Read-only file system" again when trying to do write operation.

i tried manually running the following after the "Enumerate" button press in hen:

mkdir -p /media/sda1
modprobe ntfs
mount -w -o uid=29999,gid=29999,utf8,dmask=027,fmask=137 /dev/sda1 /media/sda1
mount -o remount,rw /media/sda1

all the commands went with no errors, and /media/sda1 is accesible in read only mode.

one more thing i did which i don't know if might affect this is add the -f -l parameters to the umount command in the "mount.sh" script (because for some reason it refused to dismount the first time).