Can a RF 433.92 Mhz transceiver communicate to a RF 433.42 Mhz Receiver?
A 500 KHz offset frequency would be substantially weakened by the filter of a decent OOK receiver at these frequencies, however, some lower cost appliances may use fairly wide receivers.

But that is really beside the point here, as the RFM69 is not a fixed frequency radio, rather it is configurable to a range of frequencies and modulation types, including the ~433.4 MHz or therabouts OOK used by a Somfy shade.  So the premise of the question comes only from misunderstanding, and is moot.

Still, your task is not that simple either, as Somfy shades use a rolling code scheme.  You will not be able to control one without transmitting a code which changes at each transmission in accordance with that scheme, and pairing your code sequence to the shade receiver.