Just ran into this trying to change a relationship for Kalamainu’u Iona. She had full Friendship and Romance bars with a character I'm playing but the relationship was Acquaintance/Best Friend/Spouse. I wanted to change that to Soulmate for the Soulmate aspiration.
I tried the relationship cheats with Kalamainu'u Iona (the apostrophe) and they didn't work, so this issue is still a problem. I was able to fix it by copying the ' character from Paka’a's name in the post by @simvasion .
I then used the Alt-0146 character in sims.get_sim_id_by_name Kalamainu’u Iona and I can confirm that the Alt-code also works.
