Stable that word caught my attention.
Your other observations were good.
I've seen tables with the same type of leg set up in a pool room.
They were 9' AMF tables in Denver.
Those tables underwood structures/framework was NOT like a Gold Crown, it easily moved lengthwise when you were stretching out reaching shot and you lower body weight contacted the top rail/and skirting.
I'd like to see the way the underframe is built, to me that's key.
I'd never by any house without looking at it's foundation FIRST.
Show us a pic of the framework underneath the slate.