In "On Beowulf and His verse Translation," Seamus Heaney is very specific about his use of the word "bawn" as a synonym for Hrothgar's mead hall. Essentially, Heaney supports the use of the word based upon the fact that the use of the word seemed "poetically or historically right." Therefore, if a particular word fell under either of these categories, he "felt free to use it."
In regards to the use of the word "bawn" in Beowulf, Heaney found its "historical suggestiveness" to the original definition appropriate. According to the Heaney's writing, the word bawn is a "fortified dwelling that the English planters built in Ireland to keep the dispossessed natives at bay." Given the bawd's likeness to Hrothgar's mead hall, Heaney could not help but substitute the historical word for the original in his own translation.
Outside of this historical adaptation, Heaney would also substitute words based upon it poetic sound. For Heaney, again disclosed in his writing, each time he reads the excerpt of Beowulf where the minstrel is singing in the hall, he pictures "Edmund Spenser in Kilcolman Castle, reading the early cantos of The Faerie Queene to Sir Walter Raleigh."
In the end, regardless of historical or poetic reasoning, Heaney ends his translation with Beowulf stating that some of the changes he made to specific words in the text were based upon the idea that it was "one way for an Irish poet to come to terms with that complex history of conquest and colony, absorption and resistance, integrity and antagonism." In a sense, Heaney simply wished to leave a little of himself and his own Irish history in a renowned and beloved text.