Create widget1 with one option and some InitialValue (no translations) -> create widget2, insert widget1 into its content -> open child widget options -> choose for example ENG language and set "Use default" = NO, enter NewValue. Insert widget2 to any page, try to change page languages:
default language will contain value InitialValue (ok);
ENG language will contain value NewValue (ok)
any other language won't contain value at all (not ok) even they have to contain InitialValue
P.s.: correct value, i.e. InitialValue, is displayed in child widget options modal for any other language - see attachment with example:
Create widget1 with one option and some InitialValue (no translations) -> create widget2, insert widget1 into its content -> open child widget options -> choose for example ENG language and set "Use default" = NO, enter NewValue. Insert widget2 to any page, try to change page languages: