I think the last answer to your question does not answer your question. The projector has no lens shift, only digital keystone correction. There is a clear deterioration in quality when this is applied. This restricts the positioning of the projector. Benq has a calculator for determining the optimum position.

https://projectorcalculator.benq.com

The projector has a keystone correction. This means that you can compensate for the trapezium caused by the tilt.