Based on a true story, they said, based on actual authentic events, but what does any of that matter if the actual story presented on screen doesn’t really resonate clearly or deeply? That’s the frustrating part of “Baltimore,” an intriguing but uneven new period-drama about an heiress turned Marxist revolutionary and radical, written and directed by Christine Molloy & Joe Lawlor, two Irish filmmakers (sometimes known as the creative pair Desperate Optimists) who emigrated from Ireland to England in the fraught and tumultuous 1980s during the Troubles when the IRA continued to mount their violent campaign aimed at ending British rule in Northern Ireland in order to create a united Ireland.