I agree, it shouldn’t be annotated as “Track” which does have a specific meaning. I wouldn’t annotate as Larvae myself for the reason you cited (without confirming the presence of a larva in the case).
There are some threads that touch on some of these issues:
https://forum.inaturalist.org/t/type-of-evidence-annotation/19480
https://forum.inaturalist.org/t/lets-talk-annotations/627
and probably more, but there are definitely some that discuss trying to create a new annotation for structures created by organisms.