Handle edge cases in import

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

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

**Priority**: Low/Medium

No file, test, or entry point is named in the issue. Start by locating the import validation path and inspect how filtering is currently handled; done means configurable filtering is supported with documented sensible defaults and coverage for the relevant edge cases.

Written by the indexing model from the issue text.