Achy Obejas’ new collection expands our sensibilities — “I and I alone spoke up and cried for insurrection and change,” says the speaker in “Boomerang, After Aimé Césaire,” the opening poem of Boomerang/Bumerán, a bilingual collection by Achy Obejas, published in 2021. In this book, the boomerang functions as both a thematic and formal motif. Several poems bear…