x1 is not enough/an insufficient amount/too little/too few of x2 by standard x3.
toldu'a is the shortcoming/shortage/what is absent of something by some standard; moxna is that which is present, even though it is not enough. In other words, moxna and toldu'a are complements of one another (such that they sum to sacni). See also: toldu'e; dukse, ranlu, sacni, moxna; mo'anzu; mo'a.