An analysis of the infamous New Zealand writing question

Im aware that theres a debate raging on College Confidential over the following question from the October SAT, and Id like to weigh in: Although New Zealand (had fostered) music for decades, it was not until the 1980s (when) musicians began (to reach) an international audience. (No Error) First, the sentence should correctly read as follows: Although New Zealand had fostered music for decades, it was not until the 1980s THAT musicians began to reach an international audience. Before I start in on why when is wrong, Id like to go through the other options being debated: 1) had fostered In this case, the past perfect is correct because it describes an event in the past (fostering music) that clearly occurred before a second event (musicians began to reach an international audience). Now, the present perfect (has fostered) could also work, implying that New Zealand is *still* fostering music, but theres nothing in the sentence that demands it rather than the past perfect. Remember: if two options are both grammatically acceptable, neither can be considered wrong. Style and personal preference dont count. 2) to reach To reach = infinitive. Infinitives get flipped with gerunds. Began reaching is also fine, but it isnt inherently better than to reach (if anything, its a bit more awkward). Same issue: two acceptable options, both fine. (Btw, I have no idea what the last option was Im going by the version of the question that was sent to me and that I found on CC.) Ok, here goes for why when is wrong. Its actually a question of standard usage more than anything else. The fixed construction is it was not until x that y occurred (the other variation of the phrase would be the inverted verb structure not until x did y occur). What ETS has done to confuse everyone, however, is to insert a decoy relative pronoun, when, which looks and sounds as if it could be correct because its placed immediately after a date (1980s) and everyone knows that when is supposed to refer to dates. The problem is, however, is that the fixed construction It was not until x that y occurred trumps everything. Its like a word pair (e.g. not onlybut also): you just cant separate the two parts (at least not in SAT land). Thats whats actually being tested, even if it looks like something else. (Side note: ETS often uses when to create incorrect logical relationships. It frequently replaces a stronger, clearer conjunction such as however or because.) Now, to add a further level of complication, there is a situation in which when could be legitimately placed after the date, namely if a non-essential clause were to be inserted. For example: Although New Zealand had fostered music for decades, it was not until the 1980s, when new forms of media technology became widespread, that musicians began to reach an international audience. But note that this version still includes that! To be fair, its a very hard question, as well as an unpredictable one by SAT standards, but theres absolutely nothing unfair or subjective about it. Standard English usage requires that, not when, be used with it was not until. If someone were to write that sentence in a paper and use when rather than that, it would still be wrong. As a matter of fact, its the kind of error that college professors see in students writing all the time. And thats exactly why it was on the test.