I have successfully sent OSC commands to Qlab and to Luminaire from Watchout.
I found out that you must send 2 sets of 3 hex 00 separated by a comma, so an OSC command would look like "/cue/1/start$00$00$00,$00$00$00"
At least that's what I had to do for simple commands like that to those programs. I haven't done anything more complex.