Calan sits next to 5 phonetic neighbors — Caelan, Kalan, and Calen are the closest matches by sound. Most share Calan's Welsh cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"first of the month, calends"
"destroyer of enemies, world peace"
"ash tree clearing"
"the people"
"boundless, countless"
"God is gracious (via Zane/Zaid roots)"
"joyful, jovial (from the same root)"
"from the city of Troy"
"variant of Jason (healer)"
"hound, warrior"
"lord, sovereign"
"friend, companion"
"strength of God"
"slender"
"white, fair-complexioned"
"one who strides, walks with purpose"
"the river that swallows all rivers (from Zaire/nzadi)"
"modern invented name, possibly eight (from Octavian)"
"split, torn apart"
"courageous, valiant"
Similar sound: These names share phonetic patterns with Calan — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin via Welsh origins, giving them the same cultural heritage as Calan.
Rhythm: Calan is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.