I highly support this feature suggestion!
I’ve had the same thought, also sparked by the confusion around そう (and a few others, less memorable off the top of my head).
In fact, I’ve gone on a bit of a vocab-adding spree, with a significant portion of vocabs added based on grammar points that use them (or are basically identical to them).
I’ve found that this ‘multi-angled attack’ has both helped me comprehend the grammar points, and to recall the vocabs, each ‘angle’ reinforcing the other synergistically.
If grammar points literally linked to their related vocabs, doing this would be quite a bit smoother, and would make a clear case for Bunpro’s decision to include vocab, and to try to unify the vocab/grammar item interfaces. (Likewise for vocabs linking to respective grammar points if they exist.)