You are viewing Buddhist practice through an absolutist lens and therefore misunderstanding it. Sunyata negates the kind of absolute you are referring to. Sunyata is incompatible with comforting concepts like "God" and "cosmic consciousness".
That's just how it is, and no amount of woolly syncretism will gloss over this distinction.
Probably another thread, but I think syncretism is rather dubious. It means denying the differences between different traditions or misrepresenting what they say. It also relies on the superficial notion that all spiritual paths head in the same direction, a claim which I think can easily be challenged.
Wasn't talking about "practice." Was talking about "enlightenment."
Sunyata is all about finding peace, rest, comfort from suffering/lack of contentment. Same goal and path any human being would follow to eliminate suffering and find peace, rest, and comfort. If someone experienced finding rest, peace, and comfort and called it finding "God," or finding "cosmic consciousness," why would this offend you? Why take away the diversity and respect only certain words?
Your idea of syncretism is more centralized on different exoteric practices, traditions. My idea of syncretism is centralized on the enlightened internal. All human beings have that in common.
If it's dubious, you shouldn't worry about mere words such as "God" or "cosmic consciousness." You are denying the differences yourself and misrepresenting what they say.
You're taking mere words far too seriously.