Right now, the positions for the anchors do not take into account things like transforms, offset-path (position: sticky, which is covered by #8448).

In practice, there were cases in my experiments where I wanted to use those — transforms and offset-path for the animations/transitions (see the animations for the “four quadrants” in my article — I want to attach things that move, but because transforms or offset-paths are not used, I have to animate things via top and left).

Currently, specs do not mention any of these cases — if those are intended to not be supported, the specs should be clarified, but I would suggest looking into providing an option to somehow follow those.

I understand that for the transforms and offset-path things are probably much more complicated — but I foresee a lot of cases where developers would want an option to follow those. I wonder if this could be something like anchor-transform or whatever, which could be optionally used with transform on the anchored element? And maybe something similar with offset-path (though, maybe it could be similar to position: sticky in that it is easier to describe how it could work by default?)