There are thousands of named and published & registered with the Royal Botanic Garden at Kew cultivars of Japanese maple. Just as with a pedigree dog, you loose the papers (name tag or provenance) you just have a mutt. If you purchased this tree at ''generic maple'' price, then you came out good. If you paid a premium because it was a named cultivar, unless the seller can get you the name, you are out of luck.
Identifying it from photographs is not considered ''valid'', there are thousands of named cultivars, many cultivars look very similar. Guessing is not good enough to re-tag the tree return to using the ''pedigreed'' name.
Now if I had to guess, this looks like a Matsumurae type of Acer palmatum, possibly it was 'Grandma's Ghost' or 'Mikazuki' or 'Sister Ghost' It could be a number of other cultivars. The dark central vien, and the pale green then the dark outer edge is a similar pattern, many cultivars have this basic pattern.
one reference to see a bewildering number of different varieties is