Tiger barbs are often used as dither fish in cichlid tanks but it does depend on the size of the tank and what tankmates they have, I noticed your stocking in your sig and the BGK when larger could become a threat to the barbs. Jewel cichlids can also be particulary aggressive towards smaller fish and so they may also become a problem when they mature. The convict in a large tank shouldn't be ok, but there is always the risk. Lastly your severums are likely to get to at least 7 or 8" if not bigger so at that size they may also turn on the barbs.
I think it would work with larger barbs for a time, but with the other species you have you can't be sure that things will stay that way.