I started with the disclosure that we all believe consciousness exists in some form.
Do we?
That alone separates my argument from your example: consciousness exists, Florgleblorp doesn’t.
How can we even assign properties to something which has no meaning?
That’s how scientific investigation frequently works. We recognize phenomena before we fully understand their mechanisms or develop reliable criteria for identifying them.
No, that's not how scientific investigation works. Even if we do not fully understand something, we can still fully define what it is we're talking about. We can concretely define what a banana is, such that you and I can both agree upon what is and isn't a banana, long before we have any detailed physical analysis of the underlying chemical properties of a banana. Not understanding something in perfect detail doesn't prevent you from giving a high-level definition which defines it in terms of its surface-level qualities.
I don't even see how we can investigate something to begin with if we cannot even identify what it is that we're talking about. That's why I think you missed the point of my Florgleblorp example... if I told you to go investigate Florgleblorp, how would you even do that, if you have no idea what I'm even talking about, because I've not even given you a definition loose enough to identify it?