perhaps this will partially do want you need.
filter -xnswwc @debug -
filter -rww $filtered $+ - $+ $filtered @debug @debug2 *
the first filters everything from the status window into @debug with a linenumber in front of it (except lineseperators).
Then it filters everything in the range of "number of filtered lines" to "number of filtered lines" from the @debug window to (yet again) the @debug window. This gives you the last line of the status window into @debug with a linenumber in front of it to identify it. This gives you at least the ability to see if a NEW message was given in the status window (including error messages or echo's from script or whatever). It's only a small part but i think it's also the only way to catch any errors. Perhaps it can be done a lot easier since i'm not very familiar with /filter