Perhaps reading customer reviews might help. Below are links to two soaps with Himilayan sea salt as an ingredeient, with several reviewers that state their skin suffered lacerations using a soap made with Himilayan sea salt (sold on Amazon).
https://www.amazon.com/Himalayan-Sa...p_d_hist_1?filterByStar=one_star&pageNumber=1
https://www.amazon.com/Spice-Lab-Hi...r&reviewerType=all_reviews#reviews-filter-bar
As far as your other question about research on grinding salt, I have not read any specifically about that, but I really don't know what search parameters to use to get the most applicable results. How the words are strung together in a search makes a big difference when searching. Also which words are used and not used can limit or enhance a search. If you have a leaning toward certain scientific journals, searching them specifically might help (or not.) Perhaps you could contact Dr. Kevin Dunn and ask if he has any ideas of who may have done any such research, you will probably get a response. He is a chemist who has done extensive soap-related research, published many papers, books and done multiple lectures on soap making topics.
