How to call custom variables in Email template?

I have created 3 profiles in Profile for all 3 environments (test, uat & production) and trying to call the variable (G_SiteURL) in Email Templates under Project–>Settings using the below syntax.
${GlobalVariable.G_SiteURL} but email itself is not triggering.

Even i tried from katalon documentation for Subject and same also not working

please suggest.

Hello, I have a similar problem. I can create variables and these are also displayed correctly in the fields for Sender, Recipients, Cc, Bcc, and Subject (as described in the documentation), but if I want to use these variables in the template, it does not work. Since I am now simply assuming that this was not fundamentally intended, my question is whether there will be a solution in the near future so that the templates can also be edited with variables?