unfortunately it will not work, I had this problem too. The syntax is unfortunately not correct.
I know, if you query your current configuration via GET, then you get as you see in the picture. If you want to import the config via PUT, then it must look like this:
"comment": "Allow TCP traffic to subnet with HTTP servers.",
And most importantly, where I had been looking for the solution for a long time, I wanted to change the first SSID for me and entered number 1 as the SSID. This is unfortunately wrong, because the SSID numbers start with 0. I configured a wrong SSID all the time 🙂