Kelso sits next to 3 phonetic neighbors — Carlisle, Kelsey, and Kelson are the closest matches by sound. Most share Kelso's Scottish cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"chalk ridge, chalk farm"
"courtyard, enclosure"
"craftsman, skilled maker"
"gift from God, he who is sent"
"combination of ke- (prefix) and Marion (beloved)"
"born of fire, handsome chief (via Kenneth/Cionaodha)"
"small flock, family group"
"new house, bright place"
"small fort"
"authority, firm determination"
"beloved one"
"reddish-brown color"
"creative coinage blending Da- prefix and Kai (sea)"
"one who fights in combat"
"of the river (if -von is from Welsh afon)"
"beloved of Yahweh"
"tailor, cloth cutter"
"red-haired, auburn-haired"
"blazing torch, flaming sword"
"Greece, Ionia (land of Greeks)"
Similar sound: These names share phonetic patterns with Kelso — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English origins, giving them the same cultural heritage as Kelso.
Rhythm: Kelso is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.