The absolute location that the book the 43rd War takes place in is
Moeri probably did not mention the name of the country because she didn't want to be confined to curtain historic details and wanted to be able to add a little bit of fiction. When she talks about the war she probably had different examples from different Central American countries put together, so even though she put different experiences together it was all true.
Citations:
moeri, louis. the 43rd war. NY: Hougton miflin, 1989.
"Atlacatl." Wkipedia. 2007. Wikipedia. 28 Jan 2008