It seems extremely likely that Donald Jr. lied to the committees about the Trump tower meeting. The question, then, is: were the lies "material"?
The false statement must be material to the proceedings. A false statement is material if it has "a natural tendency to influence, or is capable of influencing, the decision of the decision-making body to which it was addressed." Kungys v. United States, 485 U.S. 759, 770 (1988)(denaturalization proceeding). The testimony need not have actually influenced, misled or impeded the proceeding.