I'm aware that you can use
[#1234] syntax in posts on drupal.org issue pages.
However, is there any syntax to point to the specific comment, like:
I was using it before, but I forgot the syntax and I can't find it anywhere.
References to project issues in the form of
[#1234-2]for comments) turn into links automatically
That is from the very bottom of compose tips.
So just replace the colon with a hyphen and your guess would have been perfect.