Perhaps add just an open field for notes on a profile. I don't know of another slicer that has this. For example, perhaps under the Other tab just add a box at the bottom that will accept any input and only store that info with the profile. Personally, I'd use it to note the max/min of certain settings for that printer or filament type. I have one for PETG and might make a note that the max speed my printer can us would be 110mm/s. I could also enter the temps for different brands PETG, etc.
If you need a workaround for now, you could always add your comments at the beginning of your starting script. Just place a semicolon beforehand and the machine will ignore it.
; comment line 1
; comment line 2
remainder of starting script...