I don't see a problem.  Seems to work fine.  If the TP qualifies for one of the credits you enter the amount on NJ1040 line 37a,b,or c.  If you exceed the limitation for the particular credit you get an error. If the TP exceeds the income limitation you get an error. 

Otherwise it's just a direct reduction to income on lines 39 & 42 and that works too.