The spelling of the word "Simonna" is based on the pronunciation of its constituent sounds. Using IPA phonetic transcription, we can see that the first syllable is pronounced as "si" /si/, with a short "i" sound, and the second syllable is pronounced as "monna" /ˈmɒnə/, with a short "o" sound. The final "na" is also pronounced with a short "a" sound /nə/. Therefore, the spelling of the word "Simonna" accurately reflects its pronunciation.