I was wondering if the Holy Smite spell stacks (with blindness for a round) each time it is used?

Don't remember, but I'd guess the CRPG reddit pages or a site like RPG Codex is a better place to ask this question than the GOG general forum. Just trying to be helpful, not an attack at all.

There's this as well here:

https://www.gog.com/forum/icewind_dale_series#1616628785