Kepler sits next to 4 phonetic neighbors — Keller, Keefer, and Kemper are the closest matches by sound. Most share Kepler's German-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"hat maker, cap maker"
"coal settlement; dark farmstead"
"he will laugh, laughter, one who laughs"
"supplanter, one who follows at the heel"
"from the east, eastern settlement"
"courtyard, enclosure"
"battle settlement"
"fame and glory"
"the great river (via Zaire)"
"creative spelling of Legend (things to be read, from Latin legenda)"
"faith, reliance, confidence"
"God's beauty (Jah + beauty)"
"friend of horses"
"son of Max, son of the greatest"
"The Lord is my God"
"son of Will"
"great peace"
"high, noble, strong"
"noble, distinguished"
"son of one with a bright mind"
Similar sound: These names share phonetic patterns with Kepler — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have German origins, giving them the same cultural heritage as Kepler.
Rhythm: Kepler is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.