You can do this with a few shortcuts in sublime. It requires about the same number of keystrokes, but far less cognitive overhead.

    { down { down {

to insert all three leftmost brackets.

    up up up

to go to first bracket.

    shift+left

to select first bracket.

    cmd+d cmd+d cmd+d

to select all three next brackets including the first.

    ctrl+shift right

to move all three cursors to the end of word.

    comma space "

to type your characters with all three cursors.

    cmd+right

to go to end of line with all three cursors.

    " } ,

to type your characters with all three cursors.

21 presses (29 keys), compared to your 32. And all I had to think about was where the cursor was.

(Not to be pedantic, of course!)