The features list claims MAVLink messages are supported by the script. However, I don't see STATUSTEXT (253) MAVLink message is displayed (I see it in GCS). It seems like only default ArduPilot messages are shown.
ArduPlilot 4.5.7
FrSky Tandem X18SE
ETHOS 1.6.0
YAAPU 1.3.0 (fc8f523)