My guess - that variable name is just not correct utf8. You can freely use most weird variable names without "strict":

${"weird var name even with a space in it!"} = 'qwerty';
print ${"weird var name even with a space in it!"};
[download]

That code works, and even stranger variable names will work without "strict".

To be more specific, what exactly hexadecimal codes of that strange variable name?

Courage, the Cowardly Dog