My initial plan was to post one complete review, but it's going to be bits and pieces as I go now.There's a rounding problem when accepting someone's offer. I entered the Maximum Exchange Amount (BTC):

When I entered that amount, I didn't realize it would lead to a XMR amount that's higher in the 6th decimal. Result:

When I tried again, the maximum BTC amount was a few sat lower, I copied the Receiving Amount (XMR), I could create this deal without problems:

TL;DR: in my first attempt, the BTC amount should have been accepted, and the XMR amount should have been adjusted to the Maximum to get.