Potentially, once again, an example of two peoples separated by a common language

I've been caught in the past, when ranting about grammar. I've been informed that what I saw as an irritating construction that knocked me out of a story, is actually a perfectly valid construction elsewhere.

So, I'm once again asking, instead of complaining.

Does this read as a valid sentence construction to you?

---- He could imagine a place where he and X were stood, side by side.

or this one -

--- They were sat on the floor.

or this -

--- The stone had sank in the water



Right *looks at clock* I'd better get off to work. Thank you for any thoughts. I'll be back tomorrow morning.