Virtually none of the W-24 engines were all that reliable. They developed the Allied Allison V-3420, which consisted of two V-1710 Allisons in one crankcase. It was a decent engine but, like all the W engines, if it developed an oil leak, the oil quickly went down to a hot exhaust pipe with predictable results.
The German DB 610 that powered the He 177 had it's own share of oil fires, largely caused by the fact that the inside and outside valve covers and other bolts were hard to reach, making keeping them tight with regular torque checks extremely difficult. Since the aircraft HAD this issue, the expedient of going to a 4-engine layout as in the He 277 seems to me SHOULD have been rather obvious. It had the disadvantages of slightly greater profile drag and slightly reduced roll rate due to the inertia of wing-mounted engines, but this was a bomber after all, not a fighter, and the decrease in roll rate should have been a non-starter as an issue. The advantages were a hugely-reduced chance of inflight fires and a large jump in engine reliability compared with the DB 610. Otherwise, it SHOULD have been about a wash.
The thing is, engine reliability and in-flight fire events were MAJOR in the He 177 operational lifetime.