Midi is always delay compensated and independent of the audio anyway. If everything works correct it gets a timestamp upon entering the system.
AFAIK only onboard converters are 100% correctly delay compensated by the driver, like when you use the UFX analogues.
With the madi and digiface converter latency is not compensated automaticely, since the driver can not know the latency. But this is not in the audible range but  in the few samples range.

At least some MADI devices support delay compensation, that e.g. all Octamic XTC (e.g. up to 8 chained after each other) will have the same latency so that you can connect two mics (for stereo) to two different XTCs and which will have the same time base.
Delay compensation is only possible for the RME devices following the old "8-port" scheme, see e.g. Octamic XTC manual for "delay compensation". But not newer devices with 12 ports like 12Mic. Then you need to connect 2 mics for stereo recordings best to the same preamp.

BTW, things like delay compensation were special extensions from RME for MADI when in the old days up to 8 XTCs have been connected to a MADI bus.
Nowadays a 12Mic has a higher port densities, so you connect only fewer number of devices, esp. at double speed.
And the converter latency additionally became a little smaller.
So that the latency in total through MADI is not so high anymore compared to 8x XTC in the old days.

Thank you very much!

So, for example, if I liked the M-1610 Pro and wanted to use it as my "interface" via a madiface USB, I would need to manually add delay compensation if I need that. A case where I might need sample accurate compensation is if I use outboards and want to mix it with the original audio. In that case, I believe transients benefit from sample accurate timing but I have not experimented with small errors like 3-4 samples.

Wouldn't it teoretically be possible for the interface to report the latency of the slowest connected converter and hold the internal converters/faster converters so that everything gets delivered at the same time to DAW? Then the drivers wouldn't need more then one latency value.

Thank you very much for sharing your knowledge!

I started thinking about midi delay compensation again. I understand that it will be correct within the midi world but what if I send midi to a synth and get audio back?
I’m working like this a lot and it’s always a hassle because the timing always gets wierd in my current setup (non RME) and the delay is also different depending on buffer settings. Will this workflow be any smoother with built in midi in the UFX II for example?

I understand that the interface can’t do anything about latency in the synth but it could perhaps compensate for it’s own midi output and audio input?