On a stock RHEL (6) installation, when OpenOffice.org runs in headless mode (effectively disabling fontconfig), Chinese characters included in Latin texts don't get replaced with UMing family glyphs (which is the Chinese font of choice in RHEL and other Linux distributions).
Situation seemed to improve in a later LibreOffice commit that added some UMing substitution, but that was not quite sufficient (did not work in spreadsheet with zh-cn characters) for me.
I'm including the patches with changes I've done to make things work for me with some guesswork and attempts to be consistent across Chinese variants.
Created attachment 63769 [details]
[PATCH 1/2] Fall back to AR PL UMing CN for zh-cn text
Created attachment 63770 [details]
[PATCH 2/2] Fall back to AR PL UMing variants on presentation and spreadsheet, etc. as well
Created attachment 63772 [details]
maybe this would work better ?
Are you able to test this patch ? i.e. enable fontconfig font and glyph substitution for the headless case. It it works that'd be the ideal solution methinks.
Caolan McNamara committed a patch related to this issue.
It has been pushed to "master":
Resolves: fdo#51693 use fontconfig font/glyph substitution in headless mode
hopefully that fixes it by using fontconfig replacements on headless mode too
*** Bug 49035 has been marked as a duplicate of this bug. ***