I see two different sets of symptoms on those leaves, so I think you have two different issues to contend with. 
In the second photo (IMG_9224), it looks like damage from lace bugs (Hemiptera, family Tingidae). There is no way to know for sure from the photo, but you could inspect the underside of the leaves for the telltale fecal tar spots. These would be tiny black spots that are very shiny and hardened, like shellac or varnish. You should be able to see them easily with a 10x hand lens or loupe. If you think it is lace bugs, my advice would be to wait until the eggs hatch in late April or early May. At that time, you can monitor the underside of the leaves for the nymph stage. Nymphs are small spiny insects that will also be visible with a hand lens. They don't fly and they will be fairly sedentary on the underside of the leaves. Once you see nymphs, you can use an insecticidal soap to kill them. You will have to spray directly on the underside of the leaves. Be sure to follow all label directions on the product you choose, to ensure its effectiveness and the safety of yourself and others. Insecticidal soaps leave no residual so they will need to be re-applied as needed through the spring as the eggs laid last year will continue to hatch for a period of time. If you'd like more information, here are some online resources, for you to consider:
Lace bug article from MSU Extension: https://extension.psu.edu/lace-bugs-on-broad-leaved-evergreen-ornamental-plants
More about lace bugs on broadleaf evergreens from Penn State University Extension here: https://extension.psu.edu/lace-bugs-on-broad-leaved-evergreen-ornamental-plants

The other photos show what look like some of the pretty common foliar fungal diseases that show up from time to time on these plants (e.g. Cercospora leaf spot). They are more or less a sign that conditions were good for fungal diseases last year and it might be a good idea to implement some simple cultural management practices to prevent the issue from persisting. Pruning out affected leaves/branches now and cleaning up fallen leaves will do a lot to reduce disease incidence next season. A protective fungicide spray could be used in the spring, but that is probably not warranted unless the infection rate is really high. You can read some general information about these kinds of diseases in this article from University of Maryland Extension: https://extension.umd.edu/resource/fungal-leaf-spots-shrubs/
And this page from Penn State, lists some common rhododendron diseases: https://extension.psu.edu/azalea-and-rhododendron-diseases