The part you've quoted from the help file applies to the action Replace with regular expression and not to the other actions (that's why it's only noted there).
I dd. As I said in the report, "On V2.49, Help is modified to accord with behaviour."
Sorry Florian, but faults in behaviour/docs such as this are very much issues to users such as I having to deal with multiple versions due to recent changes that have made different Mp3tag versions incompatibile with each others' scripts and configurations.
By the way, your marking of this as (No Bug) is inaccurate. It should be [F] (Fixed Bug).
It rejects the range of versions I am using, 2.44-2.54, with "You entered too much data for the field 'Mp3tag Version'", so I have set it to "-" for now.