I think your intentions with the compost and daily watering were good, but their effects were quite the opposite.  Planting in native soil and watering deeply but infrequently (perhaps twice weekly for the first year at most) is the way to go.  Most likely the plant is suffering from root rot, which means even though you're backing off on the watering, it is lacking the healthy roots it needs to provide water to the leaves.  Couple that with hot weather and it's not good.  My recommendation is to dig it up, and if the roots look reasonably healthy, try planting it in a pot and keeping in a guarded environment for the rest of the summer where it won't have as great a demand for water as it would out in the open.  If the damage thus far is too severe, it won't make it, but that is true of leaving it where it is too, so you have nothing to lose by potting it up.  If it survives, try re-planting in the spring in just native soil.  Save the compost for a mulch on the top.