There are several synonyms for the phrase "leaped in to breach". Some alternatives include "jumped into action", "stepped up to the plate", "took the lead", "filled the void", and "bridged the gap". Each of these phrases illustrates someone who has taken charge and stepped forward to fix a problem or address a needs. The phrase "leaped in to breach" in particular implies a sense of urgency and daring - someone who is willing to take risks and make bold moves. Utilizing different synonyms can help to convey similar ideas with slightly different connotations, adding nuance and depth to a piece of writing.