i consider that extremely minor leaf damage.. and in august.. i expect such ...

personally i wouldnt do anything about it ...

i believe your assumption of it spreading from one family of plants to another.. is not right ...

but there could be regional PNW issues i am not aware of ...

ken

Pests and diseases tend to be species- or genus-specific, don't get on multiple different unrelated plants in the vicinity. This is sun burn, and is concentrated near the building wall due to heat reflecting off of it. The remedy is likely to give the planting bed a good soaking, probably it is not moist enough for the plants to be able to endure hot days - such as we have had a few times this year - without damage. The lack of recent new growth on the vine maple and the somewhat dull or pale appearance of the viburnum would tend to indicate the soil has been on the dry side for awhile - a very common occurrence in this climate at this time of the year.