The spots on the hydrangea are very common this time of year and are caused by an array of fungi and occasionally bacteria; this particular one looks like Cercospora, which is a fungus. Even so, fungicides are not warranted and the infected foliage can simply be collected and disposed of once it sheds this autumn. Fungicides are preventative measures only, intended to protect uninfected foliage, so cannot cure existing infection. (Plus, tissues that look clean so far might actually be in the early stages of infection but still asymptomatic, so treatment won't always work.) 

The pruning to open them up for air circulation is a good start. Otherwise try to water at the base of the plants and not splash water or soil on the leaves since there could be fungal spores in the soil still. Try to keep the leaves dry beyond when it rains. In the fall collect and dispose of the leaves. In the meantime just know the infected leaves wont pose a major threat to your plants and these are mostly cosmetic issues. 

Emily