Something still does not add up.
Are you using some form of file server to access remote files? I am puzzled by a few things.
First:
If you were to drag the folder, as you say you did, after the cd command, it should have looked like this:
iMacIntel:~ Nous$ cd /Users/Nous/Bureau\ :\ iMacIntel
instead of
iMacIntel:~ Nous$ cd /Users/Nous/Bureau \:\ iMacIntel
There should be a backslash character BEFORE the space and immediately after the word "Bureau". You have the backslash AFTER the space.
You ended up in the right folder, anyway, which is weird. The unescaped space ought to have been read as a separator.