For a new membesr/swappers, I think it can be confusing to have a button saying to "turn down" a swap, after the other has confirmed (maybe by mistake). Because some people, will see it as; do I then have to open a new swap?
I'll think, and I'm not alone, the swap will then be closed and denied. For that reason, in my opinion, it will be a good idea to rename the button "renegotiate". Renegotiate is a word with less room for interpretion, so that's a good idea, especially for all the non-english natives, I think.
Especially if it's a swap with a lot of coins and it will be a pain in the butt, to find them again, so one will hesitate to click the turn down button, and work araound it.
A little more, where I started this suggestion, with some confusion:
https://en.numista.com/forum/topic107019.html