Just to clarify where we are... I am absolute noob in audio processing, I am just a home piano played (half seriously educated when I was a child) and I play for myself some other instruments (drums, guitar, violin, block-flute). But I am (hope can be called) professional software engineer, with 30 years experience and "automated controlling systems" original specialization.
With such background it is no surprise that once I have started using music software I have started to program staff. While no one would like to listed the sound I produce, my programs have some audience.
Details about X-Touch. I do not have the device, so I could not do much. Google for "XCtl pdf" and the first link will be RE results for Behringer XControl protocol, with colors support. It is basically MIDI based. When using network, they just put MIDI codes into network packets (without RtpMIDI, OSC or any other encapsulation). I have written as small utility to prove that is really working and tested it remotely. So I am sure things are working as described in that pdf. The next step had to be adding related part into AZ Controller (in fact I have almost done that) and re-map my Mackie preset to work with that messages. But at that moment Gibson abandoned Cakewalk and I have started to look for a new DAW.
If you remember, there was many threads about different DAWs on Cakewalk forum. I have started with Studio One. I have asked for an API, and they have replied "there is no and will be no". Not accessible. And so "no go".
Cubase is well known. So I have tried to ask them about API. I have got no reply. Dongles (especially under conditions Steinberg sell them) is far from something I like and Cubase is not accessible. Again "no go". They could reply there is an API and I could be on a different road by now, but that has not happened.
I care about accessibility since I met a friend which has lost his sight while using Sonar before. I have made Sonar accessible throw Control Surface integration, so I could do the same with other DAW. But I need "C" API, at least on the level Cakewalk had it.
The next DAW to check was REAPER. No "bloat" (I am an old school programmer and like that), multi-platform, open API (far above Cakewalk level), top in performance and accessible (OSARA). Final argument was the project format, so I knew I can try to write a converter. So I have started with the converter (the first and up to date the only case where you can open a project from one DAW in another, with all FXes, synths, MIDI and automations), continued with some accessibility improvements (Sibiac and small adds in OSARA) and currently in progress of AZ Controller for REAPER.
PS. Steinberg. "One step forward, two steps backward". ASIO and VST was released as open source and has moved the world. Great! But... have you ever seen related licenses? That is the only reason no DAW support more then one ASIO device. And since several months it is impossible to write any VST2 related program legally. I am going to have some troubles with the last since I need self developed vst host for one specific case and vsts in question do not have VST3 form (not to mention that writing VST3 host is more complicated then VST2).
Cubase probably was the most used DAW for a while. And it is well known pro studios use ProTools. But since "old good times" many other DAWs was written. They are smaller, cheaper, faster and has some features "traditional monsters" do not have. Down to free to use Tracktion and Cakewalk by Bandlab. I seriously doubt you can find more installations of Cubase then these newcomers. Also check "old Cakewalk users", most of them took Studio One or REAPER roads.
PS.PS. If you have some technical questions, please do not hesitate to ask. I will answer if I know the answer, or can even try to find some answers (f.e. running tests remotely on your system). But writing something Cubase specific is not in my current plans, sorry.