Excess humidity causes:

1.Improper refrigerant charge.

2.Oversized equipment.

3.Air flow too high.

4.Supply side air leakage,causes infiltration.

5.Return air leakage.

6.Building envelope problems,wet crawl space,etc..

That's all I can think of right now.Anyone else,free free to chime in!

Number 1 is possible,as well as 3,4,and 5,from what you have told us,the picyitres,and their lack of any solution to date.

Was the humidity ,high, with only 5 tons?What about the previous system,humidity wise?