During the last five days, Xfce terminal lost my keybindings (additional or changed settings for menu accelerators) three times:
They were replaced by the defaults, and accels.scm afterwards also showed the defaults instead of my settings.
It does not happen at every shutdown & restart, only now and then, it seems to depend on timing coincidences.


First problem / question: Why does this happen?

I assume that the terminal tries to dump accels.scm on shutdown / session exit,
and gets killed while doing so, which leaves a damaged, empty or nonexistant accels.scm in the config dir.
On the next startup, as there is no valid accels.scm, it resets the keybindings back to the defaults.

Please do *not* write any config file on application shutdown, this is asking for trouble.
Write config changes immediately when they are made.
I had very similar problems with several Xfce panel plugins:
They also lost their configuration now and then, and whenever they lost their config, 
a zero-length config file with a date equal to the shutdown date was left in the config dir, 
which is a clear indication that the plugin was killed while rewriting its config on shutdown.


Second problem: Lost keybindings are very hard to recreate:

* Although I have the global "change accels in the menu" config setting enabled,
gtk does not allow me to change accels by hovering the meny entry and pressing a key
(it does not work in any application, I don't know why).

* The oldstyle way of setting the key bindings in the terminalrc file seems not to work any more:
I have defined all my keybindings in the terminalrc file, too, and they are still there, but they are ignored.

* I found no GUI to set the terminal keybindings.

* Editing accels.scm directly does not work: 
I found no way to load the newly edited accels.scm into the running terminal.
Hence, the terminal overwrites my changes with the defaults when the session ends.
I would have to edit accels.scm while the terminal is not running,
but how do you vi a file without a terminal running?
(I finally did it from a text console, really messy...)