Hi xod,
thanks for your trial. (Sorry if this should be a wrong expression. My English is poor.) My printer is Canon Pixma MG5350. I used it for years printing A5 with paint.net by Windows XP, 7 and 10 - until that bloody Redstone upgrade.
With IrfanView I still get A5 - hoping Bill Gates will not read this to destroy it in his next Windows update ;-)
Regards
Eugen