The developers are very aware of the problems with BTCPay in the DEX (although it is interesting to hear them spelled out in detail). That is the reason why at the top of the Counterwallet, there is the notice: "The easiest way to buy XCP is to use Quick Buy in Counterwallet. For traditional exchanges, click here." Buying XCP with BTC should be done using Vennd (Quick Buy), and selling XCP for BTC should be done using a centralized exchange. IIRC, they announced a while ago that they are working on a solution to the BTCPay issue.
Buying and selling assets for XCP, on the other hand, works pretty well.
Ok, I'm just saying they should not have the xcp/btc exchange open right now. I've seen people complaining about it all week and it simply does not work. It should just be closed for now until they sort out btcpay because it's opening the door to financial loss for new people. That post you quoted is from august and there's no way I could find that in this thread easily. There should be an announcement about the exchange posted somewhere accessible, to discourage BTC use currently. Devs being aware of the issue, and new counterwallet users being aware, are two different things of different importance.