I concluded that the description was related to the use of the us+dvorak-alt-intl layout, and not to g-c-c setting incorrect options. Observations from use of the us+intl layout:
Alternate Characters Key to None
--------------------------------
$ gsettings get org.gnome.desktop.input-sources xkb-options
['lv3:ralt_alt']
Right Alt according to xev: Alt_R
Alternate Characters Key to None + Compose key to Right Ctrl
------------------------------------------------------------
$ gsettings get org.gnome.desktop.input-sources xkb-options
['lv3:ralt_alt', 'compose:rctrl']
Right Alt according to xev: Alt_R
Right Ctrl according to xev: Multi_key
Alternate Charters Key to None + Compose key to Right Alt
---------------------------------------------------------
$ gsettings get org.gnome.desktop.input-sources xkb-options
['lv3:ralt_alt', 'compose:ralt']
Right Alt according to xev: Multi_key
I see only expected options and expected results. So please elaborate on how you think that g-c-c behaves incorrectly, preferably with a reproducible use case.
I concluded that the description was related to the use of the us+dvorak-alt-intl layout, and not to g-c-c setting incorrect options. Observations from use of the us+intl layout:
Alternate Characters Key to None ------- ------- ------- ---- desktop. input-sources xkb-options
-------
$ gsettings get org.gnome.
['lv3:ralt_alt']
Right Alt according to xev: Alt_R
Alternate Characters Key to None + Compose key to Right Ctrl ------- ------- ------- ------- ------- ------- ------- ---- desktop. input-sources xkb-options
-------
$ gsettings get org.gnome.
['lv3:ralt_alt', 'compose:rctrl']
Right Alt according to xev: Alt_R
Right Ctrl according to xev: Multi_key
Alternate Charters Key to None + Compose key to Right Alt ------- ------- ------- ------- ------- ------- ------- - desktop. input-sources xkb-options
-------
$ gsettings get org.gnome.
['lv3:ralt_alt', 'compose:ralt']
Right Alt according to xev: Multi_key
I see only expected options and expected results. So please elaborate on how you think that g-c-c behaves incorrectly, preferably with a reproducible use case.