Relay actuator alarm siren acknowledgment

[grumpazoid]

I have built the relay actuator using the stock sketch in examples.
I think because I am using one of my "bad" NRF24L01 radios, sometimes the signal to switch it on does not get through.
Domoticz knows that it has not switched and puts the software switch to match.
This has really got me thinking and I'm struggling to put all the pieces of the puzzle together.

Questions:
Does Domoticz know if the switch request has happened or not because ACK is enabled at the Domoticz end? Child S_LIGHT/S_BINARY is set to ACK true by default. (I have not enabled ack in the sketch)
Will enabling ack in the sketch change anything?
Is there a way to keep sending the turn on request until it switches on?
If I use signing, is that another way of checking communication?
I am currently trying to learn MQTT/Node Red. Would using MQTT and QoS2 be a better way to get the signal through.

I guess the aim here is to get communication between gateway and siren guaranteed.