How long has it been since the two plants were in contact, I had what looked like much larger calyxes forming which began to reveal a very pale green seed. So my first sign was those much larger calyxes about 2-3 weeks after I think they were exposed give or take.
If you see brown receding pistils well before harvest time that is a sign of pollination. Brown receding pistils are clearly seen in your pictures. How long have you seen them and roughly how far from harvest were the plants when they first showed up?
If you have found seeds then there was at least some pollination. If you have many early brown receding pistils on many areas of your plants or only a few only in isolated areas that would give you some idea of how extensive the pollination was.