You may be overwatering them. Daily irrigation for a shrub whose parent species are not particularly thirsty sounds excessive to me, even very recently planted.

Since I have no idea of your soil quality, how well it drains and how the amendments may have affected that, I can't say for sure but the yellowing of lower, interior leaves is generally a classic sign of water stress (too much). And it is also quite possible that soils just inches away from each other drain differently. And even more likely if individual planting holes were amended.

incredible stresses of digging of ball and burlap or pulling a pot out of a greenhouse ..... shipping.. transporting to your house and planting.. and maybe e en some cold damage depending where you are.. and whether they were properly hardened off ...

and improper watering ...

no plant needs water every day ...

most shrubs prefer a sip of water .... than then near drying before the next watering.. and frankly.. i can think of anywhere in the US that needs that much water in early april.. there just isnt the heat to draw moisture out of the soil.. where the root are.. we really dont care if the soil surface dry in spring winds...dig a small hole with a tablespoon and FIND out about moisture does 3 or 6 inches...

you are on the verge of loving them to death.. just treat them like the 'run them over with the truck' plant they are.. and you should succeed.. and who cares if you lose some interior older leaves in the process ... the future is all it he growth tips...

ken