As we discussed over in https://github.com/backdrop/backdrop-issues/issues/1091, we think new users might be expecting a lot more buttons in their rich-text editor, but having a gazillion buttons might be overwhelming, so we would like to hid them in a WordPress style "Kitchen Sink" button, that will hide / show the tools available.
GitHub Issue #:
1520
Recent comments
For such cases I like EVA https://backdropcms.org/project/eva
Display field using content of another field
If you don't want/need a View, I think Computed Field would be an excellent option for this. BTW, you can use token replacement (by using the function token_replace()) in the computation of the field...
Display field using content of another field
Views would be my first port of call, but I guess you've already thought of that. I haven't used it but you could also look at Views Field Formatter
Display field using content of another field