So pleased you enjoyed them Colleen. They do work so well with that rice dish!

Sorry you're not happy with them. This recipe isn't intended to be a super liquidy one though. You can see in my photo and videos how it should look.
If they were really saucy they would be no good for tacos, salads, burritos etc. You can of course add more liquid though if you prefer them that way and that won't affect the cooking time. You might well need to up the seasonings etc if you do though because extra liquid will dilute the flavours.
My recipes are tested by me and a team of recipe testers and we all found that 25 to 30 minutes was optimum for cooking. 25 for firmer beans, 30 for slightly mushier well-cooked beans. Instant Pot themselves actually suggest 20 to 25 minutes cooking time for unsoaked black beans: https://instantpot.com/instantpot-cooking-time/#tab-id-3
If yours aren't soft after 45 minutes then it's likely to be the beans you are using. Like you say you never really know how old they are or how they have been stored. Perhaps try some from a different source next time.
In answer to your other questions, I always test my bean recipes with beans from multiple sources and my recipe testers would also have bought different beans to me. All of our beans came from regular grocery stores. I have no idea what Rancho Gordo is. We don't have that here.
Hope that helps!

I'm really pleased you are enjoying them! The reason the lime is added at the end is that a lot of the flavour disappears with cooking. If you add it after it preserves the lime flavour. Yours will be fine though and yes, you could always add a squeeze after cooking too to give the flavour a boost.

There is no specific time. Just wait until the natural pressure release has happened and the pin drops. Don't open it before that happens. Then they will be perfect. And if you don't happen to notice the pin drop it doesn't matter if they sit there a bit longer. Hope that helps!