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.
DoJ guidelines