Begin with two consonants
Common pairs reveal whether below-base forms, doubled consonants, and substitutions such as ಕ್ಷ and ಜ್ಞ are available and positioned correctly.
Increase cluster depth
Three-, four-, and five-consonant sequences are stress tests. They help expose collisions, missing substitutions, poor mark placement, or fallback from another font.
Judge shaping, not only coverage
A Unicode mapping confirms that a character exists. It does not prove that a complete cluster will shape well. Compare spacing, alignment, legibility, and consistency across each depth.