The skill picks are indeed hard coded to Athletics, Sleight of Hand, and Intimidation, and apparently this is a known issue, but the fix didn't make it into release. This is a big problem because if the skills overlap with your background, you simply lose out on the skill pick.
https://forums.larian.com/ubbthreads.php?ubb=showflat&Number=819081The warlock's pact of the tome has a similar issue where you cannot pick the cantrips granted. We should refile these bug reports so that Larian reprioritizes these issues.