Kathryn sits next to 3 phonetic neighbors — Katherine, Catherine, and Katelyn are the closest matches by sound. Most share Kathryn's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"pure, clear"
"star"
"from Brittany, land of the Britons"
"forest, wood"
"maiden of the coral sea"
"from the willow farm"
"fragrant spice"
"prosperous in war"
"flowing, streaming"
"gold"
"goddess of spring"
"driftwood"
"white shoulder (from Fionnuala)"
"strength, power"
"wild rose"
"queen, wife of the khal (warlord)"
"divine gift"
"island of wild boars (alternative etymology)"
"queen of orchids (named after William Cattley)"
"captivating, snare"
Similar sound: These names share phonetic patterns with Kathryn — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek katharos origins, giving them the same cultural heritage as Kathryn.
Rhythm: Kathryn is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.