besides the design / architecture choice, there is actually a little bit of misalignment of the UTFgrids vs the marker / grid tiles. so even when clicking with a mouse, you don’t always get the expected result.
see https://forum.inaturalist.org/t/open-test-of-map-tile-improvements/7833/88 and https://forum.inaturalist.org/t/the-selection-areas-for-a-lot-of-things-are-too-small-or-misaligned/9155/8.
also, it seems like sometimes the UTFgrids stop responding, though zooming in an out will usually solve the problem.
that said, those problems may not be easy to fix.