So chump change then.
The types of memoria I've found are:
1. Increases the ATK bonus on the card.
2. Adds a percentage chance to inflict a specific status ailment to the card's attack.
3. Increases the HP bonus of the card
4. Decreases damage taken from monsters of specific elements.
5. Increases the resistance to specific ailments.
The bonuses are all so insignificant and they take such an insane amount of time to craft. (72 hours for a +4% ATK). Memorias feel like a huge trap. They probably just exist so that players with huge amounts of resources can have something to dump all their efforts(read as money) into. For normal people they're not worth it. The game is ridiculously easy anyway. At ReLVL 50+ you can basically complete any scenario in the game on auto mode.