Similar to any other command, I would expect /return to show a feedback message in chat indicating its success and/or return values. Alternatively it should not be available in chat.
How to reproduce
Run
/return 4or/return failfrom chat❌ No feedback message appears in chat
Relates to MC-267193
I think it's best if it's not made exclusive to functions, but the result would say something about it, for example:
"Returned 3. Run this in a function to end its execution, passing /execute if function"
and
"Returned failure. Run this in a function to end its execution, failing /execute if function."
This would aid new users quite a bit in understanding what it does, without needing to resort to the wiki or alike.