Yes, I do recall that, but as always with engines I prefer to have the physical proof beyond reasonable doubt.
Seeing them in action, just a photo still of the engine with reversers engaged, would be demonstrative.
Papers do not necessarily tell us that the WS-20s on Y-20B themselves have thrust reversers, for all we know it was a study that was not implemented on the real production article.
The nacelle seems to have a small extension on the bottom, similar to what you can see under the PW1000G's nacelles

It is a fairing to cover part of the thrust reverser mechanism, so it wouldn't be far fetched to assume it has a similar role

The C-17 has a similar fairing, as well
