First shot is secondary growth flushes that got burned by weather conditions because they were made too late in the year to mature. This is not the shrub dying back, notice that the older growth below these is normal looking.

The similar damage to the older leaves in the second shot is also weather related - too much heat or cold. If the root zones are not mulched do this now, to prevent additional heating of the rooting area. Also poke around in the original soil balls and planting holes to see if soil moisture conditions are good (moist, and not dry or wet).

Of course, if this is entirely or primarily cold damage from last winter existing soil conditions will not pertain to that. Unless you find something now - like interiors of the soil balls being quite dry - that might be relevant, the plants having gotten burned during the winter because there roots were not able to take up enough water.

During any additional plantings of long term plants like trees, shrubs, woody climbers or perennial plants that you may undertake do not amend planting hole back-fill. Re-fill holes with loosened existing soil instead, with organic material applied to the soil surface, as mulch instead of being mixed into the back-fill.

I don't believe what you're seeing has anything to do with last winter's temperatures. After all, aren't the leaves in question new growth that was not even present last winter? Further, I have never seen winter injury confined to just the leaf tips. What can cause this is, confusingly enough, conditions that are either too wet or too dry or even fluctuations from one extreme to the other. A waist high rhododendron (Hardy Giant?) is a sizable specimen. It would not be unusual to find a relatively small root system and lots of top growth in a 5 gallon or larger container grown plant. If field grown, some of the root mass could well have been lost when it was dug. In other words, don't assume that the root ball remained moist because you've had damp conditions. Check the rootball. If it's too wet, improve the drainage. If too dry, soak thoroughly with just a trickle from a hose.

i also cannot agree with the planting advice above. Rhododendrons and most other members of the ericacea need to be planted in a medium that contains lots of coarse organic matter which drains well, holds moisture and allows an abundance of oxygen to reach the roots. The "do not amend" mantra is currently fashionable and may well be fine even for rhododendrons under certain specific soil conditions. Under most conditions, however, the advice of recognized rhododendron experts such as David Leach, the Coxes in Scotland, Ellie Sather at Whitney Gardens, and many others with decades worth of experience remains worth following.