First, there is a good reason why the %VAR% syntax exists. It is the Windows/DOS syntax for environment variables, and as such it is what many Windows devs are probably using (as it is the natural thing to do for them).
So with that in mind, you can't have abbreviations for batch files right now...
Second, this syntax existed well before the macros manager was redesigned and well before anything else, for that matter (revision 521).
And I really doubt anyone is using it nowadays.
Look, the problem is that different syntax for declaring variables is a half-attempt.
There are two ways that can solve most/all problems:
1) The fixed approach Have only the $(VAR) syntax for new projects. All previous versions will be either supported, or translated to the $(VAR) syntax.
Code::Blocks projects are serializable.
2) The flexible approachLet the user define multiple syntax for variables, with tokens or regexs.
Defaulting to:
$(VAR)
${VAR}
$VAR
%VAR%I personally prefer the 1) approach, but I don't mind as both solves the aforementioned problems.