Hi and welcome to the forum
Most Echinodorus species (Amazon sword plants) are grown hydroponically (wet rots, dry leaves). When these plants are put underwater, the terrestrial leaves die off and new aquatic leaves grow. This is common in new plants from pet shops. Don't remove the leaves until they are completely brown and have dropped to the bottom, then you can cut them off with a pair of scissors. Plants draw the nutrients out of the terrestrial leaves and use them to grow new leaves. If you cut the green leaves off, you are taking away the nutrients that can be used for new growth.
The holes in the leaves are quite uniform and I would say the snails and or plecos are chewing on them. Make sure you have driftwood, algae and biofilm (slime on the glass and ornaments) in their tank. Offer them slices of pumpkin, cucumber, zucchini, etc, in addition to an algae wafer a couple of times a week.
Make sure any fruit/ veges you offer are free of chemicals and rinse well under the tap before adding to the tank.
Give the tan some time and the plants will shed their old leaves and hopefully have lots of nice new ones. If the new leaves get full of holes, post more pictures.