Reading the pronunciation guide also lets you know that Kennealy-Morrison knows rather more than most people about Celtic languages and has made an effort to simplify things for the reader. She talks knowledgeably about differences between different strains of languages. And she points out where she has taken liberties with known linguistic fact to create a single language with elements of all the major Celtic traditions. Native speakers of Celtic languages will probably grimace at what she has done, but the rest of us are none the wiser for the helpful simplification. What I like most about her use of language, however, is that she recognizes that words are mutable, living things.
People change usage dependent on circumstance.
For example, a girl named Suzanne might also be known as Sue, Susie or Sukie. Those not in the know might mistakenly call her Susan. I even know one woman who prefers to be called Zanne. Writers will fall naturally into that behavior when they use familiar or near familiar names. Martin's Brandon Stark is Bran to his family, Samwise Gamgee was known as Sam.