I’ve just tested it for changing the username and it’s a few extra steps to copy paste rather than use the auto complete, but even then it seemed to have silently dropped the edit on save.
I don’t think I can use it to tidy-up the eg #sysadmin category section title when it’s not automatically made it sysadmin. It wants to open up in full edit mode. There’s no autocomplete for that, and manually changing all the bits can be quite fiddly.
For some other ones that are in the wrong section, it’s a case of cutting and pasting them into the right one (if it exists in that days summary). Not too bad on desktop, bit awkward on mobile. Though that needs a full edit window.
For regular text changes it’s not too bad, though full edit window is quite easy for that as well (as long as you can pick it out of the wall of text 
)