Alla sits next to 5 phonetic neighbors — Ella, Ala, and Alma are the closest matches by sound. Most share Alla's Russian-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"all, everything, noble"
"of the Claudian family"
"settlement of the Britons"
"to soothe, to comfort"
"bright, famous"
"from Leicester; possibly heavenly"
"shining, celestial light"
"French woman, woman from France"
"washed, cleansed; or variant of Lavinia"
"beautiful one"
"from Clare, the bright place"
"prosperous friend"
"of the Balbinus clan"
"short form of Lavinia"
Similar sound: These names share phonetic patterns with Alla — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Germanic via Slavic origins, giving them the same cultural heritage as Alla.
Rhythm: Alla is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.