Pedro Andres Aranda Gutierrez <paaguti@gmail.com> writes:

> Having said that, I was also (just a bit) bugged by the fact that
> bibliography file names are completely expanded when generating LaTeX.
> Couldn't we avoid that for LaTeX export?

It is in `org-cite-list-bibliography-files'.
AFIAU, full path is forced there to make #+SETUP containing local
bibliography path work:

---- main.org -----
#+SETUP: settings.org
------ end --------

---- ../settings.org -----
#+BIBLIOGRAPHY: local.bib
--------------------------

One reasonable option could be keeping relative paths relative iff the
#+BIBLIOGRAPHY is derived from a file inside the same directory with the
exported file.

Tentative patch attached.