Could work, but I wouldn't use the ADI-2 Pro this way.
I would use the ADI-2 Pro for the monitoring through phones and active monitors and connect the external effect using the analog inputs and outputs of your UCX II.
The quality of the analog channels of your UCX II is already excellent for adding external devices.
You have more advantages to make use of the ADI-2 Pro's features for your monitoring section
1. auto reflevel
2. 4 analog stages / ref levels to have high SNR even at lower volume settings
3. dynamic loudness is a big win when listening at lower levels
4. you can protect your ears / equipment by setting the final volume on the ADI-2 Pro. Then it doesn't harm ear/equipment if you set the output fader in TM FX accidently to 0dB. This can be supported by using attenuators to additionally fix level mismatches, see also: https://forum.rme-audio.de/viewtopic.php?id=25399
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13