Does it really matter if they cross?

For things you’re just going to be sowing & eating yourself. It’s not an issue at all. As long as the cross pollination doesn’t do something weird to make them inedible in some way. But you won’t know that until it’s too late.
I think the main reason people “professional” get twitchy about crossing is the seeds getting passed around and weakening the varieties. More technical than that, I’m not the person to explain it. You know it all anyway.
You’re definitely right. It’s pretty impossible to find any information on what happens if you let nature do it’s thing. All you can find is the really silly misconceptions about crossing of cucurbits & capsicum.
Maybe that’s you’re next mission in the garden. Write a detailed report about what happened   .