In Acrobat DC on the comment toolbar I have selected "Enable text correction keyboard shortcuts." This allows you to
put the cursor in the text and simply type missing letters/words (which shows in a comment box)
select text and hit the "delete" to put a red line through it
select text and start typing new text to replace it (which shows in a comment box)
This works similar to how CS 6 Acrobat worked, if I recall, although selection of individual tools in CS 6 was much more robust.
However, it doesn't "stick." Sometimes it works, sometimes it doesn't. Sometimes it works and then stops working. Like right now I have the "enable" option highlighted, have a word selected, hit "delete" and nothing happens.
Another behavior is that if I'm inserting text, the first letter I type is highlighted in the comment box and is replaced by the second letter I type.
It's maddening. So I just had to input about 125 corrections to a brochure and every time I had to use the mouse to choose the tool to do what I needed to do, rather than doing it from the keyboard.
This can't be happening for everyone, so how can I find out why it's happening to me? On OS 10.11.1.