EDIT: Edited the whole post to remove the history and highlight the problem and the fix I found.

Problem : Mac French version installed through Galaxy (version 55249679), launch the game isn't working. Check log through wineskin shows this error:
dyld: Library not loaded: @rpath/libwine.1.dylib
.....

Fix 1: Install Mac English version through Galaxy, it runs fine. Try change its setup to French will only get the same error than above.

Fix 2: Download the install file through the shop, Mac French version (version GOG-9). This version runs fine. in Galaxy install the game, then select More>Configure and select Manual updates and Language French eventually. Then quit Galaxy, remove the Planetscape Torment installed by Galaxy. Rename the version from shop as Planetscape Torment, and put it in folder where Galaxy had installed the game. Launch Galaxy and that's it. You have Planetscape Torment Mac French version running fine through Galaxy.

Note: The Galaxy image for Mac French version seems have a problem, thankfully not the similar version from shop.