I can see the laciness of
Cynthia! It's very 'fine', like lace or feathers or the leaves of something like fennel or dill.
Where I live it's definitely a boomer name, but I think a younger
Cynthia would be surprising but not 'bad'.
Lacey Cynthia looks better, but
Cynthia Lacey sounds better.
Cynthia and
Lacey together sound like mother and daughter, not sisters.