Is Frederick Law Olmsted widely known for Boston's Central Park?

Answer 1

If you mean New York City's Central Park, well yes - he's widely known among those interested in landscape planning/architecture.
But in Boston, he was involved with these:

"Boston and Vicinity
Frederick Law Olmsted:Boston's Emerald Necklace - Lantern Slides
The Emerald Necklace
Arnold Arboretum
Institute for Cultural Landscape Studies - Harvard University
Fairsted - Brookline

See the second link for a good overview of his works, please.