Brilliant sits next to 3 phonetic neighbors — Brylinn, Beryllian, and Brilliance are the closest matches by sound. Most share Brilliant's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"shining, sparkling, full of light"
"Pledged to God; my God is an oath"
"kiss"
"snow"
"lake, waterfall (from Welsh -lynn component)"
"sovereignty, rule"
"good person, calm"
"keeper of records, secretary"
"unique, special"
"foxglove flower"
"grace, favor"
"invented name combining La- (the) with -viah (echoing Hebrew -iah, ..."
"Her Majesty — a royal title indicating supreme authority and dignity"
"moonlight, shining light"
"born in April, spring blooming"
"dear friend, beloved companion"
"messenger of the gods, boundary marker"
Similar sound: These names share phonetic patterns with Brilliant — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have French via Italian origins, giving them the same cultural heritage as Brilliant.
Rhythm: Brilliant is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.