I think I saw the settings somewhere to turn off Art. on different parts, but now I cant find what I 'thought' I saw!
I'm still looking 20mins later!
When I trytry an SA2 voice to LH + Flugel to RH part, Art.1 gives me a 'knock' , similar on Art.2, and both stay active (flashing) until I hit a Flugel note (which is loaded as RH part.) My knock is nothing like your sound, so I guess its affected by the sound you have loaded on LH? Try a Steel Acoustic Amp, and see if you get the 'knocks', and the flashing ready for the Flugen on RH.
Bit confusing 😊
Al