How about changing FileSelect so that it accepts an optional string parameter, this being the human-readable name of the current zone. This name could then be shown along with the other zone information in the MD gui window while MD is going though the zones.
You can put a
Title command before a FileSelect that shows what zone MyDefrag is working on.
Example:
Title("$mft")
FileSelect # $mft
FileName("$mft")
FileActions
SortByName(Ascending)
FileEnd
jonib