Does DALI always need LED lamps to transmit responses to commands?

Hello,
We have DALI connected LED lamps.
Many of the lamps will not dim when DALI commands them to do so.
Does DALI need the LED lamp to be able to respond to the DALI controller? (ie does DALI always need the lamp to be able to respond and transmit back to the DALI controller?) I ask this because our DALI transmit circuitry in our LED lamp looks a bit dodgy, and I wonder if this is why DALI is not always working for us?
Other engineers tell me that our DALI transmit circuit in our led lamp is never used by the micro, but I am not sure…the following calls DALI out as being half duplex….
https://en.wikipedia.org/wiki/Digital_Addressable_Lighting_Interface

I believe that the DALI system definitely needs the receiving led lamp to be able to transmit back to the DALI controller (?)….otherwise DALI doesn’t work?
I know that our software engineer has used the “Official” DALI because he used huge DALI software libraries.
From the DALI TX schematic, it can be seen that the circuit there could never be able to transmit…because the NPN MMBT2222 would never get enough base current to be able to turn on hard enough to be able to conduct the 250mA DALI bus maximum. The supply at the diode side of the opto is just 2V5, and that can generate a maximum of about 1.5V/4k7 = 319uA through the opto diode……the CTR down that low could be as low as 0.05…..so that means about 20uA coming out of the opto transistor….never enough to be able to turn on the MMBT2222 hard enough.
So I conclude that our LED lamp is not dimming because it is unable to send back signals to the DALI controller…do you agree?

...or is it possible that our software engineer modified the DALI system that we have here so that we never need to be able to trasmit back to the DALI controller?

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As the bottom of the below web page, it seems to be saying that if you want to use DALI to set a certain light level, then you need “read/write”. I presume that means that the DALI controlled lamp needs to be able to transmit back to the DALI controller?
I presume this is because the DALI controller expects an “acknowledgement” from the led lamp before it sends the dimming level?
Presumably if the DALI controller does not receive an “acknowledgement” from the LED lamp then it just doesn’t send the dimming level?

https://en.wikipedia.org/wiki/Digital_Addressable_Lighting_Interface

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Also, our software engineer has set the oscillator frequency of the microcontroller in our application to 16MHz. Since DALI only operates at 1200 bits/sec, then why did he need to set the oscillator frequency so high?