This is a strange chapter in itself. All my custom chars basically have a strength of 12, but my female char often still can't jump as far as the other male chars in my party, BUT then when I jump ahead with the other chars, she can suddenly jump after them....
Yes, following seems to extend character’s jump capability to some extend.
Edit: yeah, one would need to figure out first, what is the minimal jump distance necessary to not make Larian levels too tedious. Forge comes to mind as one area already relying heavily on jump.
Theoretically, requiring use of spells like long jump or fly to reach harder to reach areas should be fine as long as those spells Last for long enough. However, if those spells would become a requirement for the whole party to progress or would need to be used too often, that would be annoying.