DVD players can have a default language set, when playing a DVD 'disc' which supports multiple languages it can then automatically select the language that matches your preferred choice.
I cannot speak for every computer DVD player but it seems VLC does not respect this, nor can I find an option to configure this. The nearest I could find was a thread in these forums discussing VLC on WIndows and suggesting VLC uses the language that Windows is set to.
This would be fine, my Mac is set to English UK as is my Windows PC, and this therefore equates to 'en' as far as DVD players are concerned.
However I am trying to play a PAL DVD copy of 'Star Wars Episode IV - A New Hope' which has multiple European languages and in particular DVD menus in both English and French. When I play this using 'Apple DVD Player' it does correctly use English for the DVD menu, when I 'debug' it using myDVDEdit on the same Mac it also uses English as the default based on 'System' setting. When I play it in VLC it annoyingly uses the French DVD menu.
Note: VLC itself runs and provides its own user interface in English e.g. menus and dialogs.
I could using myDVDEdit 'edit' the .IFO files to hard code the VIDEO_TS folder and its IFO files to English but likely I will encounter other DVDs that have the same issue, obviously it would be much better if VLC did things properly.
For those curious I believe Pgc 11 on this disc makes the decision which 'branch' to follow based on system/preferred language and Pgc 12 is the English DVD menu branch and Pgc 13 is the French DVD menu branch. The DVD commands for Pgc 11 in MyDVDEdit look like the following
R0 = 1
if(R10 == R0) R6 = 9
R0 = 0
if(R4 == R0) Goto 8
R0 = $270F
if(R6 == R0) Link Pgc 12
Link Pgc 15
R0 = $270F
if(R6 == R0) Link Pgc 13
Link Pgc 54
Note: I am using VLC 3.0.18 which appears to still be the latest version and this issue has applied to numerous previous versions as well.
Just checked on Windows. VLC 3.0.18 on Windows also stubbornly plays this disc using the French DVD menu, My Movies 5 on Windows plays it using the English DVD menu as does Windows Media Player.
So only VLC gets it wrong.
My guess is that VLC is not setting a 'system' value for menu, audio and subtitle defaults/preferred and hence these are likely left as empty or zero and then the DVD disc code branches the wrong way. Or worse the built-in hard coded value in VLC is indeed French. (Perhaps the programmer of this part of VLC was themselves French.)