Australia sits next to 3 phonetic neighbors — Austral, Aurelie, and Aurelia are the closest matches by sound. Most share Australia's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"southern land"
"Dark river"
"noble, distinguished, illustrious"
"famous, renowned (via Lydia)"
"from Florence, Italy"
"enclosed garden"
"rye meadow rider"
"Hardworking, industrious; prosperous"
"a jewel-bright, exotic feminine name"
"elf friend"
Similar sound: These names share phonetic patterns with Australia — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Australia.
Rhythm: Australia is a 4-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.