This tool does not auto-indent, as expected from a tool to reply to comments on talk pages. I always have to go back and fix my indentation manually, which means that at present this tool confers no benefit over simple source editing.
Topic on Talk:Talk pages project/Replying/Flow
It does auto-indent. Can you link to an example comment where it didn't do that? Perhaps you found a bug, or perhaps you were actually using a different tool than the one this page is about.
It seems to only do this on mobile: https://en.wikipedia.org/w/index.php?title=Talk:Colorado_Springs_nightclub_shooting&diff=prev&oldid=1123120279
Thanks for the example. The mobile talk page interface you used for this edit is a different tool, part of MobileFrontend. We're currently working to replace it with this tool, and I hope you'll find it does a much better job.
There is no way to enable it permanently yet, but you can try out its behavior on that page by clicking this link: https://en.m.wikipedia.org/wiki/Talk:Colorado_Springs_nightclub_shooting?dtenable=1
You can follow the progress of this work at Talk pages project/Mobile.