I'm not sure if I'd trust totally random cards, but at least you have more than one or two that work.
FYI, the F6 card list hasn't been updated in a long time and most or all of those cars models are discontinued. Remember that the product name on the card means nothing on these lists; you need to find those exact cars with those exact model numbers in order to be getting the cards that were tested.
So, my advice to F6 users who want to buy a currently available card tested by Zoom is to buy one off the list for the much newer F8n Pro. It's a different recorder, but one with a higher channel count so it stands to reason that cards that perform well in the F8n should also perform well in the F6.