You're correct. When I said "hypothetical", I really meant "speculative" or "conjectural".

That definition of hypothetical is a bit broad, but ok, I'll take it. With that definition, every scientific model is hypothetical since it is proposed and requires continuous testing and validation. Nothing remains proven forever.

Back to the original example: dark energy is a "hypothetical" scientific model, not conjectural. We are not waiting or looking to observe it, we already did measure it. It's a simplist shallow model, but the best one so far.