Improve error messages in handlers

**Description**
Currently validation lacks proper monitoring support.

**Proposed solution**
Add configurable monitoring with sensible defaults.

**Priority**: Low/Medium

Start by locating the handlers and validation paths referenced in the issue, then determine how configuration is currently represented. Clarify which validation events need monitoring, the supported configuration options, and the expected sensible defaults before implementing; done means monitoring is configurable and validation behavior is covered by relevant checks.

Written by the indexing model from the issue text.