English grammar: Past Tense
Being a native speaker does not necessarily mean that you lack some knowledge of your language. Secondly, any aggressive approach (about something that you are not even sure of) is not tolerable.
The quiz represents a simple example of dependent and independent clauses being separated by a comma while giving insight into the relationship between tenses.
It may be that the independent clause has a priority, in this case, to make it sound better but you have not listed any meaningful grammatical points against the sentence that starts with a dependent marker and separates itself with a comma.
(When she finished school, she got a job as a main assistant.
She got a job as a main assistant when she finished school.)
If you are preparing a critical comment then do it right. You can not just think that "when" can not be used for subsequent actions in past tense.
Of course, the quizzes are made to be discussed but please support your statements properly.