Metro Efficiency, Transparency, Reliability, Oversight, Accountability and Reform Act or the METRO Accountability and Reform Act This bill amends the Passenger Rail Investment and Improvement Act of 2008 to reauthorize through FY2029 the grant program for capital and preventive maintenance projects for the Washington Metropolitan Area Transit Authority (WMATA). The Department of Transportation (DOT) shall issue language to amend the WMATA Compact to establish a Metro Reform Board and transmit such language to the signatories of the compact (i.e., Maryland, Virginia, and the District of Columbia), the funding jurisdictions, and Congress. DOT shall not release any funds until it certifies that the signatories have enacted such language. DOT may make grants to WMATA to finance the capital and preventive maintenance projects included in the Capital Improvement Program approved by WMATA's Board of Directors. The bill sets forth protections for WMATA employees, including whistle-blower protections. The General Services Administration shall initiate a review of the various transit benefit programs administered by each federal department and agency with facilities located in the Washington Metropolitan Area Transit Zone for purposes of standardizing the rate of benefit for all federal employees enrolled in such benefit programs. The Federal Transit Administration shall conduct a review of its competitive grant programs. The bill establishes a Metro Reform Commission to inform Congress and stakeholders on the progress of signatories in amending the WMATA compact and increasing efficiencies within WMATA. It also modifies standards for arbitrating disputes involving interstate compact agencies.