I feel a similar way about some of the interactions I observe. As someone who isn’t particularly good at identifying anything, my greatest interests are in extracting useful information from the platform in other ways, which includes interactions between species.
Although I haven’t even added the correct fields to all of my own observations yet, I feel like iNaturalist’s contributions to GLoBI are extremely valuable, and would love to see more people using GLoBI-compatible fields on their observations.
I think it’s a shame when I see an observation of a parasitised (usually common) spider, but nothing for the parasite (which is usually far less observed)! So yes, feel free to add a separate observation for the parasite, and try to use one of these fields to link them.