Print test 6x9 book to office printer A4 sheets

As mentioned, printing centered is the way to go, but if you truly want to print to the corner of a sheet, you COULD do a Manual Tile, but you wouldn’t be able to print both sides automatically. You would have to print all the odd pages first with the Tile origin set at the top left 0,0 mark, then print all the even pages with the Tile origin moved to the left 2.637” (A4 width minus 6”). Not sure it’s worth the time and effort for 200pages ;)

Sounds like a duplex alignment issue—try adjusting flip on long edge vs short edge and check your printer’s margin/scale settings (set to 100%, no “fit to page”). That usually fixes the back side shift.

Also helps to run a quick alignment check using a file from https://printertestingpage.com/ so you can clearly see if the misalignment is coming from settings or the printer itself

Presumably your printer is not a duplex printer. It's always difficult to register a correct backup just by turning over the sheet.