While synchronous (two MOSFET) boost converters can indeed convert bidirectionally, your board isn't necessarily of the synchronous switching topology (it could use a diode instead).
In addition, that board certainly won't be regulating the input side so don't expect 12 V at the input. If it's set to produce e.g. 60 V and you backfeed 61 V it'll try to draw as much current as needed to reduce the output voltage back to 60 V, and all the energy will just end up at the input. If the input acts as a voltage source (like a battery) it will sink that current and maintain a fairly constant voltage, but if there is nothing to sink the current the input voltage will rise uncontrollably.