There are many "extended surfaces", and many "expanses", this is not specific. That is why every word in Strong's is then organized depending on the context, for example in the context of Genesis 1:6, the word means:
the vault of heaven, or '
firmament,' regarded by Hebrews as
solid, and supporting 'waters' above it.
You can't ignore context, you can't reduce a word to only it's isolated meaning, I know you don't do this with other words. For example:
Jesus said to eat His
flesh, so if you were consistent, you would have to eat His literal flesh. Flesh does mean flesh after all, doesn't it?
That is why Strong specifies depending on the context, and the verse:
figurative discourse, to appropriate to oneself the
saving results of the violent death endured by Christ,
John 6:52-56.
Not all the time, but they were right about Hebrew at the very least. They definitely knew Hebrew better than you.
So, you believe them when they say "expanse", but not when they say it is "solid". You pick and choose, right?