The leaf spot symptoms are hard to diagnose, but the Oxalis might be going dormant for the summer. (They prefer cool weather overall, and tend to spend summers in dormancy, as noted on the linked page that includes care tips.) The violet issue is unrelated, but also hard to diagnose as several conditions can create very similar symptoms. Can you photograph the underside of any of the blotched leaves?

The fine speckling on the violet leaves, called stippling, is likely due to a sap-sucking pest like spider mites, thrips, or leafhoppers. None would need treatment, especially since violets are valued host plants for the caterpillars of several species of butterfly, and any insecticide used might interfere with their life cycle. Plus, the pests listed above don't generally cause serious plant damage, and violets tend to be quite resilient.

Other than making sure they have enough water during this dry weather, you shouldn't need to take other actions. (Feel the soil around four inches deep, watering only once it becomes somewhat dry to the touch at that depth.) You can clip off individual leaves on the Oxalis that are heavily spotted if you prefer, to make the plant look cleaner, but aside from letting the plant go dormant and preparing to bring it back inside by autumn, nothing else should be necessary.

Miri