Bruce Momjian <bruce@momjian.us> writes:
> We use "cannot" and "could not" quite often in source code and error
> messages:
Yup.
> Is there any sense that we should have more consistency in our message
> wording?
There is specific guidance about it in our error message style guide:
https://www.postgresql.org/docs/devel/error-style-guide.html
(see under "Present vs. Past Tense"). I believe we largely conform
to that guideline, though of course exceptions sneak in from time
to time.
regards, tom lane