You need a picture on the back of the tank to help the fish feel more secure and to show them off better. Dark colours are better than light colours. You can buy aquarium backings or use coloured card, newspaper, plastic bin liner or anything really. Sticky tape the backing to the outside of the back of the tank.
You should try to keep tetras in groups of at least 6 and preferably 10 or more of their own kind. They act more naturally and have fewer issues when kept in big groups.
Watch the hornwort (plant) because it can fall apart overnight. If it starts dropping leaves or the stem turns brown, then remove the dead parts.
Apart from that the tank looks quite nice. How long has it been set up for?
How often do you do water changes and how much water do you change?