First suggestion will be to release more details/breakdowns about the messages in future version which will help with debugging of the issues.
Other is to have the configuration (like one in statistics) displayed in console too
Notable issues (Click through for the links for info on how to fix these problems):
CSS combine opportunities missed: 100.00%
Cache lookups were expired: 44.40%
Resources not rewritten because domain wasn't authorized: 26.00%
Image rewrite failures: 4.69%
Resources not rewritten because of restrictive Cache-Control headers: 4.11%
Cache misses: 0%
Resources not loaded because of fetch failure: 0.00%
CSS files not rewritten because of parse errors: 0.00%
JavaScript minification failures: 0.00%
Notable issues (Click through for the links for info on how to fix these problems):
Cache lookups were expired: 46.90%
CSS combine opportunities missed: 15.91%
Resources not rewritten because of restrictive Cache-Control headers: 11.30%
Cache misses: 2%
Resources not rewritten because domain wasn't authorized: 0.82%
Resources not loaded because of fetch failure: 0.00%
CSS files not rewritten because of parse errors: 0.00%
JavaScript minification failures: 0.00%
Image rewrite failures: 0.00%
Notable issues (Click through for the links for info on how to fix these problems):
CSS combine opportunities missed: 100.00%
Cache lookups were expired: 57.53%
Resources not rewritten because of restrictive Cache-Control headers: 14.97%
Resources not rewritten because domain wasn't authorized: 10.73%
Cache misses: 5%
Resources not loaded because of fetch failure: 0.00%
CSS files not rewritten because of parse errors: 0.00%
JavaScript minification failures: 0.00%
Image rewrite failures: 0.00%