Event files, created by a sensor trigger ( G-sensor / moment ) or you pressing the manual event button found on dashcams, the files often go to a separate folder often called RO ( Read Only )
But what ever your camera do the file should then be protected from the normal routine of the camera overwriting oldest footage to make room for new stuff when the memory card are full.
Mind you some systems also do the same for event files, but it is not like you only have room for 5 events in the memory space set aside for event files, so you should not need to worry unless you run a stupid small memory card.
As you have a 2 channel system you should be running a 128 GB memory card, anything less i would say is too small for such a system,,,,,, and some sellers would sell a 16GB card for such a system, which i find a insult to general intelligence of mankind.
The energy saving mode also confuse me a little, but i also have absolutely no user knowledge of the brand of camera you have, so i can only make general observations / recommendations.
But it should not do any harm to try it out, depending on what mode of trigger you use for parking guard you can always test it ( sneak up on car in low light for testing motion detect ) or kick wheels and push car body to try and trigger G-sensor if you use that.
Most dashcams when in parking mode and stand by you can look in the side window and see by a LED what mode it is in, so you know when to try something out.
When you find low voltage cut off, you will have some voltages to select in between, i would not use a setting under 12.2 volts, it will either be a switch on the hardwire kit or a setting item in the cameras own menus.