In the previous house we bought, the sellers took the outdoor recycling bins and dustbin, clothes line, curtain tracks and poles, light bulbs, all light shades (there was not expensive light fittings, just cheap paper shades) and plants from the garden that had 'sentimental value'. I refuse to accept that the sheer volume of plants and shrubs that they took all had sentimental value.
In the current house that we live in, the seller took loads of things, but I was expecially gutted that he took a clothes airer type thing in the utility room that was on a pulley that came down from the ceiling. i had never seen one before and thought it was fantastic. But it wasn't there when we moved in.
The seller also tried to negotiate the price of thinsg that he was willing to leave. Strangely enough, we didn't want to pay £350 for a four year old wall mounted bog standard bathroom cabinet, or £850 for 10 year old curtains.
There's nowt so strange as folk.
At least you know, OP, what the seller is intending to take, and you can take a view from there. If it were me, I would go back to the agent ratehr than the solicitor (the agent has more interest in this sale going ahead, as they are paid on commission only when the sale proceeds) and say that you were very surprised at the extent of things the seller planned on taking, and could they give it some more thought.