What is the meaning of pg_restore output?

Hi PG community,
I have questions about pg_restore output.

At some point of time in pg_restore output was such phrase "*pg_restore:
setting owner and privileges for <RELATION_NAME>*", then it disappeared, it
seems, when upgraded from PG 9.6.2 to 9.6.6
Other phrases "pg_restore: processing *item *3615 DEFAULT id
pg_restore: creating DEFAULT "public.id"
are observed if pg_restore is executed with flag -j N (where N > 1)
and aren't present when -j 1 (or without -j)

So main questions are:
1. What is the meaning of this phrases?
2. Are they documented somewhere?
3. Is it possible that output change from version to version?

Why I am asking?
I saw a script which does pg_restore and grep some of this phrases as
SUCCESS indicator that pg_restore passed OK (+ something like grep -iv
"error").
script doesn't use pg_restore exit code because, as I understood from the
authors, in the past were situations that pg_restore returned 0 code but
didn't restore of db.

Any answers, hints are welcome :).
Thanks

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