(ffmpeg - Audio) Two streams, One Channel, Two Languages
Hello erik and thanks for your answer.

Well, I finally (partly) succeeded to get a proper command. I had to precise the codec of the audio streams (MediaInfo).

So now, I have :

ffmpeg -ss 00:00:00.00 -t 00:10:00.00
-i G:\input.MOV
-filter_complex "[0:a:6][0:a:7]amerge=inputs=2;[0:a:14][0:a:15]amerge=inputs=2"
-metadata:s:a:0 language="kor" -metadata:s:a:0 title="Stéréo - Version Originale"
-metadata:s:a:1 language="fra" -metadata:s:a:1 title="Stéréo - Français"
-c:v copy
-c:a pcm_s24le
G:\output.MOV


And it works as expected !!!

The only two small problems I still have :

1. [Parsed_amerge_0 @ 000001f8f0340240] No channel layout for input 1

I just don't know how to set a chanel layout...

2. In the output result, video became stream 3 and not first as it should properly be.

They are not big deals but if I want to be perfect in what I'm doing ;)

Thanks again !!