Use macro inside CloudFormation Conditions

I've written a macro (called BucketChecker) that takes in an s3 bucket name and checks if it already exists. The fragment will return true or false accordingly.

I would like to use this macro in a Conditions section as described in this article: https://cloudnineapps.com/blogs/cloud-computing/how-to-create-dynamic-condition-expressions-in-aws-cloudformation-using-macros/.

The idea is to use this as a condition in my template like this:

Conditions:
  CreateBucket:
    Fn::Equals: ['false', 'Fn::Transform': {
      Name: BucketChecker,
      Parameters: {
        Operation: 'bucketExists',
        BucketName: 'my-bucket'
      }}]

Resources:
  MyBucket:
    Type: "AWS::S3::Bucket"
    Condition: CreateBucket   # -> only create it if doesn't yet exist
    Properties:      
      BucketName: 'my-bucket'

But cfn-linter gives me the error: E8003 Fn::Equals element must be a supported function (Ref, Fn::FindInMap, Fn::Sub, Fn::Join, Fn::Select, Fn::Split)

My main question is: is it even possible to achieve this using CloudFormation? If yes, what's wrong with my template? The linked article seems to be doing exactly the same, but mine doesn't work.

Based on the comments.

The cfn-linter was incorrectly classifying the Fn::Transform as malformed.

Deploying the stack confirmed that there are no issues with the Fn::Transform.