The tests should have negative weights based on how often that issue encountered and impact. The 2. SPI should have like 8 negative points out of 10 as most common blocker. And whole test inverse score.
My weighting system there scores the number of pages affected by SPA and caps the possible score at a "D" or "F" depending on the proportion of pages affected: https://afdocs.dev/interaction-diagnostics.html#spa-shells-i...
I've tried to weight things appropriately in assessing actual sites, but for the test here, I more wanted to just let people see for themselves what types of failures can occur.