That is fine but depending on your other stocking you may already be fully stocked and not able to handle another shoal of fish, can you give the exact numbers of fish you have? The length of the tank would be good to know as well.
50 gallons is a pretty good size tank to keep them in, I think if you got 4 or 5 more and maybe moved some of the auqascape around to create new territories that they should be okay. Now, as mentioned, with angels it's really hit or miss so that's a risk.
yeah barbs can get nippy on low numbers, I would aim for 8-9 and they should be good, i have 20 tiger barbs in a pond right now and they treat my 8 inch jack Dempsey just like one of them including the fin nipping lol, so it can also depend on individual personality. but all in all you should be good with a couple more.
yeah the point of having alot is so they are aggressive to each other but not other fish and they WILL beat each other up buts just how they establish their pecking order, they wont kill each other though.
When you get a decent amount and they get settled and confident you will find they will be swimming all over the tank and trying to eat you like piranhas every time you feed or move something. My favourite fish. I have got greens, albinos, regulars, long fin rosys, and Odessa in there too though.