Vein brown

Those leaves are looking perfectly normal and overall is looking very good! If you're afraid of fabric pots becoming too dry, you just need to be very patient when watering, take care to cover all the top and wait for the water to slowly go down, instead of filling the top and the water running down the sides and not moisting any soil at all. Also, remember to water 10% of the pot volume, so a 20 liter pot needs 2 liter water at least every water, you will see some rundown but it should be minimum if you are careful enough to moist all the soil in the pot. Amazing plants, keep on the good care!