Please change the furniture in their living quarters so she doesn't become stuck again, maybe when you aren't there, unless you've already taken care of that. And do give them a spot where they can give birth in privacy. Just in case they both go into labor at once, you might want to make it a large one.
They are pretty large, but I think they still have growing room. I had baby skinny pigs many many years ago. I think depending on how the object pinned her, the babies may have had enough wiggle room to position themselves by the ribs or more to the back area.
What you are now going to watch for is possible early labor or still birth. As for the gestation period they look close, but it also depends on if they are growing a big litter or larger babies in a small litter. I would recommend not feeling the area to much , as you don’t want to cause stress , early labor or dislocation to the babies.
remove all objects that can cause danger to the moms and babies. Put the cages in a quit area. I would put a towel over the enclosures. And just leave the door visable to see from it.
If all goes well, the babies will be walking when you see them after they are born but do not disturb them once they are born, so that the mother can adjust and feed them.
Are these Guinea pigs first time moms?
I think the babies will be okay, but there’s always a small chance, it was good that you caught the problem right away. Hoping for the best for the mom and cavies.