What's the result of gsettings list-keys org.cinnamon.desktop.default-applications.terminal in a terminal?
Also try gsettings list-keys org.gnome.desktop.default-applications.terminal in case your system uses the GNOME setting(s) instead.
If either show exec-arg but the equivalent isn't showing up in the dconf editor, you could try changing the list-keys to reset. Make sure you back up your dconf before doing this on the off-chance it's corrupted and this makes it worse.
Likewise gsettings has a set subcommand that changes values. Similar "have a backup" caveats apply. (I'm not expecting that it is corrupt, but better safe than sorry).
Worst case scenario here is that you have to create a [shell/Perl/Python/etc.] script (assuming that will work) or C executable (almost guaranteed to work, but a pain) that execs the necessary command with the required arguments and then give the name of that to the exec key in the dconf.