OK, I was confused because the engine type 6165CV is a 12 cylinder V-engine, but the 8200CV for class MT (not 8220CV as you wrote) is an 8-cylinder V-engine.

Correct - 8200CV is for MT.

Only 2 engine serial numbers (341 and 342) are mentioned for the 12-cylinder V-engines for La Meuse.

Yep - the only two engines made for a single high speed train. The other "sister trains" had engines from other makers. Clearly the SNCB wanted to test various engine types.

MP had 6175CA engines.

True - my bad.