I'm loathe to use it in shrimp tanks, especially at high doses. That said I have done it, and have only killed shrimp when I got way too heavy-handed with it trying to eradicate BBA (which has a decidedly higher tolerance than HA). If you measured and observed carefully, I think your shrimp would be no worse for the wear before you got to the point HA would die off. As for long term effects such as life span, egg production, and general vigor; I doubt anyone really knows. There is a threshold of glut that will wipe out shrimp so it stands to reason that exposure to doses under that may have some impact on their health. But fortunately glut has a short half life and works quickly so hopefully you could keep exposure to a minimum and still achieve your goals. And Neo shrimp are really good at making more Neo shrimp.
I don't know your setup or how easy it would be to do in your situation, but I've found that soaking plants and hardscape in a solution of water and glut to be very effective. And of course manual removal of HA is possible if you take your time. Another hobbyist shared with me that his trick when trying to remove anything from algae to duckweed was to take a week. On day 1, remove all you can. On days 2-7, remove more than half every day. By that last day there's very little to be found and unless conditions are prime for it to grow back, you're out of the woods. It's a lot easier and more thorough than spending hours all at once.
Best wishes and please keep us updated.
Nothing good happens fast in an ecosystem.