I forgot to specify that, if you have not defined a search template, the last search you ran should use the [matches the FoxTrot Query] criterion; or you can create a search template using this criterion, and specify this template from AppleScript:
tell application "FoxTrot Professional Search"
search "secret memo `\\b\\d\\d/01/\\d\\d(\\d\\d)?\\b`" using template "my FoxTrot Query template"
end tell
(and the FoxTrot Query syntax uses grave accents to delimit regular expressions, and not acute accents as I said)