מעין המאורע

In chapter 2 of Taanit Yerushalmi (I think it is halachah 2, but maybe 3)it is mentioned that during a Taanit, as on other special days, we must mention מעין המאורע, what is special about the day.  A rule is given:

• If we are talking about something in the past, the mentioning goes in Hodayah, where we mention Chanukah and Purim.
• If we are talking about something for the future, the mentioning goes in Avodah, where we have Ya'aleh v'Yavo.  This includes Tishah B'Av, where we daven for the future.

This is obviously different from the accepted halachah today, wherein the additino for a taanit goes in שומע תפילה.

It should be noted that this is the maskanah after a machloket, and none of the other opinions are akin to what we do, though I can give a little pilpul:

One opinion is that we mention like we do on the night and day of Shabbat.  That is to say, the middle brachah.  This is taken in the mefarshim to mean the 4th brachah, the first of the middle set.  What if it means the last of the middle set, in which case that would be שומע תפילה.  Just a thought.