is a chart that sets out most of the possibilities.
In my quite limited experience, many literary magazines don't really care all that much if you secure the rights to a given poem or two that may be under copyright. Even some that say in their guidelines that you must obtain permission, when push comes to shove they don't really require it. As a practical matter, it's hard to imagine legal action against a small literary magazine that publishes one or two poems. When publishing a book, however, things are different, and if the publisher is a large one then they are sure to have lawyers who hold you to strict legal compliance.
What I suggest you do right away is find out who holds the rights and contact them to ask permission. To protect yourself, don't concede that any copyrights exist. Just ask, in substance, whether they would be willing to let you publish translation of any poems that happen to remain under copyright protection. If their answer is yes, get them to grant formal permission and you don't have to worry about the copyright term.