Additionally, just focusing on E1 and B1 ignores possible losses in M3. For example, I believe binaryfate (correct if wrong) is out like almost 100 BTC worth of XMR that he deposited but was not credited for.
There are no M3 losses. All deposited M3 was and is fully accounted for (now held in Gringotts). binaryFate deposited XMR and sold the M3 to arbitrage B1 - he is owed BTC.