Galyn sits next to 4 phonetic neighbors — Galen, Gaylene, and Cailin are the closest matches by sound. Most share Galyn's Welsh cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"calm, serene; of the valley"
"peaceful ruler (Dutch form from Ferdinand)"
"hope"
"sweetly gentle"
"maiden, young girl"
"Judged; vindicated"
"Possibly related to sword or fire brand"
"brooding, sullen"
"blessed"
"charm, allurement"
"gift of God (folk etymology)"
"Free one; from France"
"Judge; one who judges"
Similar sound: These names share phonetic patterns with Galyn — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek/Welsh origins, giving them the same cultural heritage as Galyn.
Rhythm: Galyn is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.