For example, the Bang shortcut is bound as:

bind all <$::modifier-Shift-Key-B> {menu_send %W bng}

bind all <$::modifier-Shift-Key-b> {menu_send %W bng}

and the menu item:

$mymenu add command -label [_ "Bang"]     -accelerator "$accelerator+Shift+B" \
        -command {menu_send $::focused_window bng}

With the English keyboard mapping, the $::modifier-Shift-Key-b fires and the menu item's command is ignored (expected behavior).

With the French keyboard mapping, the $::modifier-Shift-Key-B fires AND the menu item command fires. It seems as though the capital B doesn't get matched to the menu accelerator binding.

The German keyboard mapping behaves the same as the English one.