Regular AppleScript doesn't have a progress bar, you would need to use something like ASObjC Runner or roll your own using a Cocoa-AppleScript application. However you decide to implement a progress bar, one way to get the progress from curl would be to redirect the shell script output to a file and use that to update your progress bar.
Thanks for you answer. I have another way to show original curl progress, but I have to get the result from AppleScript in bash shell, that result is a 2d array, how can I get it easily?