Hmm, it is interesting that you can change any bonus card type to a higher category according to the 1:5 ratio. But a little strange that this rule does not work in the opposite direction

That is, you would like to change a more valuable card for a few simpler ones? Also, remember that all cards can be bought and sold on the internal marketplace of the platform:
1) without restrictions
2) not lower than the baseline prices of a card, whether the value is for collectible cards or it has a par value.