Ecumenism isn't a policy of intellectual appeasement. Nor does it demand that we overlook real differences. Most of us would agree that repressing disagreement isn't healthy in our personal relationships. Nor is it healthy for our relationships with other faiths. Recognizing and addressing conflict is a necessary precursor to understanding.
Ecumenism is about sharing and respecting faith.
Ecumenism promotes understanding, tolerance and cooperation among religions in general and Christians in particular. Ecumenism isn't about ignoring the chasms that separate us or pretending differences don't exist. Apologetics can help bridge the chasms. Often the differences between Catholicism and Protestantism aren't as vast as they appear. Some of the criticisms of Catholicism are based on misinformation or in some cases, disinformation.