Japanese maples prefer moist, well-drained soil. In East Texas, soil pH is neutral to acidic so it will not impact it. Planting a Japanese maple in amended sandy soil that has been properly amended can work well, but consider that sandy soil drains quickly and may not retain moisture or nutrients as well as needed. You never said if you were frequently testing the soil moisture when droopy and how was it. JMs are susceptible to root rot if planted in soil that remains waterlogged. Sandy soil naturally provides good drainage, but amending it with organic matter can further improve drainage while still retaining some moisture for the tree's roots. Both Japanese maples and red maples have similar shallow root systems that can compete for water and nutrients if they are planted too closely together. The roots of a red maple tree (Acer rubrum) can extend beyond the tree's canopy. While the majority of a tree's roots typically grow within the top few feet of soil and could extend horizontally well beyond the canopy's edge, some grow vertically and penetrate deeper into the soil.
