Yes, it is important.
the } are part of how .json’s are written… if you write a .json wrong SH will not load it causing all sorts of problems for your mod.
this post here i give a basic rundown how .json’s work and are written 
… Question: How do you add objects to r188? - #14 by honestabelink
as a side note…
It is very common to make mistakes when writing .json's.
I use http://jsonlint.com/ to help me find the error’s.