Yeah, when I was trying to get Spiritomb in BDSP, I found it annoying that there was no easy way to keep track of who you already spoke to. But, it's still much easier than in D/P/PT. I remember that in D/P, though, you had to enter and leave the underground numerous times if you wanted to do it over and over again with the same person, though.
But Legends is rather annoying, and getting Spiritomb in any game is, really.
Except the Pokewalker, where you can get one after 10,000 steps in like on course in the Pokewalker (but who even uses their pokewalkers in 2022, no one).