There's no option for that at this time, but will add a feature ticket to add a language key to be able to override globally all values for an option.
forge.joomlapolis.com/issues/8992
Basically I aim to have it support the following, which currently does not work.
PLAN_OPTIONS_SELECTED_USERLICENSES_P
PLAN_OPTIONS_SELECT_USERLICENSES_P
For now you'll just have to use the full global below.
PLAN_OPTIONS_SELECTED
PLAN_OPTIONS_SELECT