EmailTemplate Variable in Subject

In the following link it seems to be possible to use CDATA blocks in the Subject.
https://community.sailpoint.com/t5/Technical-White-Papers/Email-Template-Usage-and-Customization/ta-p/78164#toc-hId-1728847685

So I tried the following code:

<Subject>
  	<![CDATA[ 
		#set($currentMonth = $spTools.formatDate($certification.getActivated(),"MMM"))

		#if($currentMonth == "Jan" || $currentMonth == "Feb" || $currentMonth == "Mar")
			#set($quarter= "first quarter")
		#elseif($currentMonth == "Abr" || $currentMonth == "May" || $currentMonth == "Jun") 
			#set($quarter= "second quarter")
		#elseif($currentMonth == "Jul" || $currentMonth == "Aug" || $currentMonth == "Sep")
			#set($quarter= "third quarter")
		#else
			#set($quarter= "forth quarter")  
		#end

		<html>
			<body>
				This is the $quarter
			</body>
		</html>
	]]>
  </Subject>

And I still can’t get the quarter value.
Is it possible to use CDATA blocks in the Subject? If so, what am I doing wrong?