I was actually going to edit my post to acknowledge, to be fair to UAD, that they did fix the issue with 6.4 in an expeditious fashion. In fact, earlier than their announced deadline. That is always a smart customer astonishment move for which they deserve credit.
This whole matter may not be an issue in reality. But either their legal team or someone did refine their language on their website and it is apparently a move to narrow down their representations from the past.
I respectfully request that they take a look at that language, take into account what they told you, and see if a better revision of the language would work.
I agree, they cannot make guarantees on future updates. But they can endeavor and make good faith efforts to be compatible with Sonar. That is where I believe some refinement of their language on their website would be wise.
I am optimistic here.
Below is what UAD has posted. I believe it can be "wordsmithed" a little better. Certainly they deserve an opportunity to take another attempt at writing it.
"UAD Powered Plug-Ins are compatible with VST, RTAS, and Audio Units host applications, and are widely used with a variety of major DAW software — including Pro Tools, Logic Pro, Cubase, Nuendo, Live, Sonar, and more.
However, due to plug-in host differences between DAWs — and our own rigorous testing standards — Universal Audio
officially tests and qualifies UAD v6.4.0 software only with
Avid Pro Tools 10 (32-bit) and
Steinberg Cubase 6 (64-bit).
FAQ: Does this mean that my DAW is not supported? A: We can only fully qualify so many DAW applications, and generally any VST, RTAS or Audio Units-compliant host application should work with UAD plug-ins. Also, any ASIO or Core Audio-compliant application should work with Apollo. That said, if you are experiencing issues with your UAD or Apollo on a DAW that we don't list as qualified, you can still contact tech support and log the issue with us. We absolutely want to know if something is not working for you, we have great relationships with all DAW manufacturers and will continue to work with them to understand why an issue is occurring."