Names, aliases, mustache lambdas

About this topic I asked a more specific question yesterday(*), but here a more general approach:

Is there a way to mangle the value of variables in mustache via some sort of function?

Also, in the specific case of tags, I saw that there are two variables: {{name}} and {{tag}}. According to the doco {{name}} is an "Alias for tag". So can I somehow tweak how this alias is generated, say always cut of "cat-" from its value if the value always starts with "cat-"?

(*) But I'm not sure whether the other question "drowned", because I myself had added a comment which appears as an answer...