You’re hijacking a thread… but it’s still short, so I haven’t lost the overview yet :-)
On my system, your layout installs without any problem, so the file itself seems OK.
Maybe you have remnants of an older copy of the keyboard layout lying around in some places, blocking your use of the new one?
Others on this list know better how to deal with that, but iirc doing a Safe Boot (hold down Shift during startup), then a normal one, can sometimes fix that situation.
By the way: Don’t you need the circonflex dead key for words like même ?
In other words: If you like, you can describe your motivation/target with this custom keyboard layout, so we can understand what you’re aiming at, and possibly suggest easier or better ways to reach it.
For reference, here’s a screenshot with the "missing" circumflex dead key highlighted.