Sylvester sits next to 4 phonetic neighbors — Silvester, Chester, and Lester are the closest matches by sound. Most share Sylvester's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"of the forest, wooded"
"companion, friend"
"liberator of men; freer of man"
"hunter"
"dark as a raven"
"one who serves"
"club, mace (Germanic surname root)"
"oak woodland settlement"
"dark one, man from the dark sea"
"chief, brave man"
"settlement by the sea"
"God is gracious"
"held by the heel"
"buck's meadow, deer clearing"
"he judged, he governed"
"Great, magnificent, venerable"
"Lord, have mercy (liturgical)"
"settlement by a bird-trap"
"battle"
Similar sound: These names share phonetic patterns with Sylvester — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Sylvester.
Rhythm: Sylvester is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.