Bert sits next to 4 phonetic neighbors — Burt, Bart, and Berta are the closest matches by sound. Most share Bert's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"bright, famous"
"pledged to God, God is my oath"
"lame, limping"
"worthy of admiration"
"numbness, the narcissus plant"
"variant of Cinda/Cindy"
"shining, celestial light"
"flowing, moving freely"
"Noble and famous"
"elf counsel"
"from Leicester; possibly heavenly"
"prosperous friend"
"bright, clear, famous"
"meadow on a ledge"
"fierce in battle"
"horn, strength"
"blooming, fresh, green"
Similar sound: These names share phonetic patterns with Bert — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Germanic origins, giving them the same cultural heritage as Bert.
Rhythm: Bert is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.