The Artscroll footnote on kinna 27 actually addressed this.

After mentioning that some versions have 26 and 27 reversed, and the subject in 27 makes an appropriate introduction to 26, the footnote continues

According to our sequence, this kinnah comes later because its main theme is an event that occurred after the Destruction, as related in Pesikta Rabbosi (27): When Jeremiah returned to Jerusalem he met a woman sitting on a mountaintop, clothed in black, her hair disheveled. 'Who will console me?' she cried out. Jeremiah responded sternly, if you are a real woman, speak to me, but if you are a spirit, depart!' 'I am your mother, Zion!' the woman responded. Jeremiah said to her 'God, Himself, will console you! Mortal men built you and mortal men destroyed you. But in the future, God, Himself will rebuild you as Scripture states: The Builder of Jerusalem is Hashem (Psalms 147:2).

The Artscroll footnote on kinna 27 actually addressed this.

After mentioning that some versions have 26 and 27 reversed, and the subject in 27 makes an appropriate introduction to 26, the footnote continues

According to our sequence, this kinnah comes later because its main theme is an event that occurred after the Destruction, as related in Pesikta Rabbosi (27): When Jeremiah returned to Jerusalem he met a woman sitting on a mountaintop, clothed in black, her hair disheveled. 'Who will console me?' she cried out. Jeremiah responded sternly, if you are a real woman, speak to me, but if you are a spirit, depart!' 'I am your mother, Zion!' the woman responded. Jeremiah said to her 'God, Himself, will console you! Mortal men built you and mortal men destroyed you. But in the future, God, Himself will rebuild you as Scripture states: The Builder of Jerusalem is Hashem (Psalms 147:2).

An idea I had is this: Both kinnos are written in the past, after the destruction had already happened. This follows the the events as found in the pisichta to Eicha Rabbasi 24.

In #27 we find

Jeremiah said to Hashem

מה לאב שהגלה בנו.

When Hashem responds and tells him to go to the Avos and Aharon and Moshe he also speaks in the past tense

זאבי ערב טרפו את השה

Again in Jeremiah's response to this he speaks of a nation already in captivity

והרי הם בשבי

Kinnah 26 also started off in the past tense

אָז בַּהֲלוֹךְ יִרְמְיָהוּ עַל קִבְרֵי אָבוֹת וְנָם עֲצָמוֹת חֲבִיבוֹתמָה אַתֶּם שׁוֹכְבוֹת בְּנֵיכֶם גָּלוּ וּבָתֵּיהֶם חֲרֵבוֹת

The story in thePisichta is also written after the fact

אמרו לו בן עמרם אי אתה יודע שבית המקדש חרב וישראל גלו

All in all, this doesn't exactly answer why to mention his having gone before mentioning his being commanded to, it does however seem to mitigate the problem.

The Artscroll footnote on kinna 27 actually addressed this.

After mentioning that some versions have 26 and 27 reversed, and the subject in 27 makes an appropriate introduction to 26, the footnote continues

According to our sequence, this kinnah congress later because its main theme is an event that occurred after the Destruction, as related in Pesikta Rabbosi (27): When Jeremiah returned to Jerusalem he met a woman sitting on a mountaintop, clothed in black, her hair disheveled. 'Who will console me?' she cried out. Jeremiah responded sternly, if you are a real woman, speak to me, but if you are a spirit, depart!' 'I am your mother, Zion!' the woman responded. Jeremiah said to her 'God, Himself, will console you! Mortal men built you and mortal men destroyed you. But in the future, God, Himself will rebuild you as Scripture states: The Builder of Jerusalem is Hashem (Psalms 147:2).

The Artscroll footnote on kinna 27 actually addressed this.

After mentioning that some versions have 26 and 27 reversed, and the subject in 27 makes an appropriate introduction to 26, the footnote continues

According to our sequence, this kinnah comes later because its main theme is an event that occurred after the Destruction, as related in Pesikta Rabbosi (27): When Jeremiah returned to Jerusalem he met a woman sitting on a mountaintop, clothed in black, her hair disheveled. 'Who will console me?' she cried out. Jeremiah responded sternly, if you are a real woman, speak to me, but if you are a spirit, depart!' 'I am your mother, Zion!' the woman responded. Jeremiah said to her 'God, Himself, will console you! Mortal men built you and mortal men destroyed you. But in the future, God, Himself will rebuild you as Scripture states: The Builder of Jerusalem is Hashem (Psalms 147:2).