I tried messing around with the tmlanguage file to fix the syntax highlighting for variables but I count not get it to work.
THIS DOES NOT HIGH

LIGHT
match
($)[a-zA-Z_][a-zA-Z0-9_]?\b
name
variable.script_variable.local.filemaker
match
($$)[a-zA-Z_][a-zA-Z0-9_]?\b
name
variable.script_variable.global.filemaker