AWS Transfer Family named variable list

Hi, Where I can find the AWS Transfer family named variable list. I am looking for all lists specifically SourceIP. Here are some examples I found in AWS documentation.

${Transfer:UserName} or ${Transfer:UploadDate}

https://docs.aws.amazon.com/transfer/latest/userguide/API_CopyStepDetails.html I am interested in getting the source IP of the user. Any other option to get SourceIP other than the CloudWatch log? I can see SourceIP in CloudWatchLog but reading the CloudWatch Log entry takes a longer time to return the query.